From 67e04cfead9fe2cc53d7169aeab96d8126bbef39 Mon Sep 17 00:00:00 2001
From: roytam1 <roytam@gmail.com>
Date: Thu, 9 Nov 2023 16:35:18 +0800
Subject: [PATCH] import changes from `dev' branch of rmottola/Arctic-Fox: -
 Bug 1236750 - Introduce a new unit type CSSTransformedLayerPixel. r=kats
 (4e9bba3d19) - Bug 1236750 - Add a ViewAs() overload for casting (with a
 justification) one typed matrix to another. r=kats (c48e143508) - Bug 1236750
 - Add some specialized typedefs of Matrix4x4 to represent layer transform
 matrices. r=kats (cc50113c98) - Bug 1239300 - reject promise with null while
 creating imagebitmap from empty blob; r=smaug (bff7483bf1) - Bug 1233056 -
 Long tapping on a link will select a different link from the page r=tnikkel
 (3a727b33c1) - Bug 1245674. Null-check mGlobal before dereferencing it in one
 more place in Promise code. r=smaug (68cf5312dc) - Bug 1236750 - Use
 strongly-typed matrices to represent layer transforms in APZ code. r=kats
 (63931eb2a1) - Bug 1236750 - Add typed getters for layer transform matrices.
 r=kats (baef978fe1) - Bug 1147673 - Relax the ancestor transform assertion a
 little. r=kats (ec9ce47ba4) - Bug 1154161 Initialize
 WidgetQueryContentEvent::mReply r=smaug (6086291313) - Bug 1240921 - Use
 nsAutoTArray in nsStyleSet::RuleNodeWithReplacement. r=bz. (66f6823b46) - Bug
 1229437 part 1 - Add a helper function to get the float containing block of a
 given frame. r=dbaron (72de452e5d) - Bug 1229437 part 2 - Reparent floats
 inside pulled ruby segment. r=dbaron (82cc44632d) - Bug 1229437 part 3 -
 Support iterating frames of RubyColumn. r=dholbert (5d43e7f6ff) - Bug 1229437
 part 4 - Reparent floats inside pulled ruby column. r=dbaron (4c1a7ff20b) -
 Bug 1229437 part 5 - Add crashtests for this bug. r=dbaron (6afabe1604) - Bug
 1229437 followup - Fix sign-compare error in RubyColumn::Iterator on CLOSED
 TREE. (e93453d00a) - Bug 1229437 followup 2 - Fix another sign-compare error
 in RubyColumn::Iterator on CLOSED TREE. (c0bf6a2a7b) - Bug 1229437 followup 3
 - Fix a mistake in RubyColumn::Iterator::SkipUntilExistingFrame(). a=me
 (1ce408e194) - bits of Bug 1072150 - Use the opt-out for various sloppy
 consumers (29d97c59ca) - Make test_bug946632 compatible with asynchronous
 scrolling. (bug 1140293, r=mstange) (e975a8350c) - fix misspatch of 1072150
 (a3e580fa4b) - Bug 686281 - Implement nsStyleImageLayers; r=dbaron
 (85bb33c8e6) - Bug 686281 - Rename *background* to *imagelayer*; r=dbaron.
 (36d90f112d) - Bug 1230034 part 4 - Make FramePropertyDescriptor to be a
 template. r=froydnj,dbaron (271cd19b6e) - Bug 1230034 part 5 - Convert all
 frame properties which use DeleteValue and ReleaseValue as destructor to be
 typesafe. r=dbaron (efc8d63c9d) - Bug 1230034 part 6 - Convert all frame
 properties which do not hold pointer to be typed. r=dbaron (b5541775f7) - Bug
 1230034 part 7 - Convert nsIFrame::GenConProperty to be typed. r=dbaron
 (2b71527b2c) - Bug 1230034 part 8 - Convert frame properties which assert on
 destructor to be typed. r=dbaron (0f125a3414) - Bug 1230034 part 9 - Convert
 FrameLayerBuilder::LayerManagerDataProperty to be typed. r=dbaron
 (1147498c2f) - Bug 1230034 part 10 - Convert remaining frame properties to by
 typed and remove the unsafe declaring macro. r=dbaron (d59d94eac4) - Bug
 1072501: Unmap file mapping on source surface destruction. r=jrmuizel
 (19fd63890a) - Bug 1235613 - Make gfxCriticalError/Note strings in gfx/
 unique. r=jrmuizel (780c6ff862) - Bug 1247535 - Fix -Wunreachable-code
 warning in mfbt/Poison.cpp. r=froydnj (0e7cf60b6d) - Bug 1239479: Add
 comments to mfbt/XorShift128PlusRNG.h from the RNG's designer. DONTBUILD
 r=Waldo (bb674b07ce) - Add an assertion message to the assert-is-empty in
 LinkedList::~LinkedList, to indicate to users who hit it that it's the fault
 of the caller, not the fault of MFBT code. No bug, rs=froydnj (4cad80874c) -
 Bug 1221103 - Add a comment to nsIChannel::securityInfo noting that this info
 may appear on non-nsHttpChannels and how that may happen. r=bz IGNORE IDL
 (cd9cebc3f2) - Bug 1001765 - Make login credentials in Saved Passwords
 manager editable. r=MattN (09eec4f6f8) - Bug 1188478 - Add an Import button
 to the password manager to open the browser migrator. r=dolske (d1126a89fc) -
 Bug 1199382 - Rename some strings from "password" to "login" in preferences
 and the manager. r=markh (60638f5e2a) - Bug 1207733 - Update @disabled on the
 Remove Password button when selection changes. r=MattN (64ac9f22f6) - bits of
 1124472 and 1166840 (26e2681183) - Bug 1219707 - fix argument passing to
 migration.js, r=jaws (55d332f5c6) - bug 1215657 - make
 AccessibleWrap::get_accSelection work with proxies=davidb (4e72111032) - fix
 missing telemetry entry (4fcfabb3e6) and follow-up API changes of TFF#493.

---
 accessible/windows/msaa/AccessibleWrap.cpp    |  12 +-
 browser/components/preferences/security.xul   |   6 +-
 .../chrome/browser/preferences/security.dtd   |  10 +-
 dom/base/nsContentUtils.cpp                   |   2 +-
 dom/base/nsDOMWindowUtils.cpp                 |  18 +-
 dom/canvas/ImageBitmap.cpp                    |   6 +-
 dom/canvas/test/imagebitmap_bug1239300.js     |  19 ++
 dom/canvas/test/imagebitmap_on_worker.js      |   5 +
 dom/canvas/test/mochitest.ini                 |   9 +
 dom/canvas/test/test_imagebitmap.html         |   2 +
 .../test/test_imagebitmap_on_worker.html      |   3 +
 dom/events/Event.cpp                          |   2 +-
 dom/events/test/test_bug946632.html           |  50 ++--
 dom/promise/Promise.cpp                       |   8 +-
 dom/promise/Promise.h                         |   2 +
 gfx/2d/DrawTargetD2D1.cpp                     |   4 +-
 gfx/2d/Factory.cpp                            |   6 +-
 gfx/2d/SourceSurfaceD2D1.cpp                  |   4 +-
 gfx/2d/SourceSurfaceD2DTarget.cpp             |   4 +-
 gfx/layers/BufferTexture.cpp                  |   6 +-
 gfx/layers/LayerMetricsWrapper.h              |   6 +
 gfx/layers/Layers.cpp                         |  12 +
 gfx/layers/Layers.h                           |  12 +-
 gfx/layers/LayersTypes.h                      |  17 ++
 gfx/layers/TextureDIB.cpp                     | 129 ++++++---
 gfx/layers/TextureDIB.h                       |   2 -
 gfx/layers/apz/src/APZCTreeManager.cpp        |  28 +-
 gfx/layers/apz/src/APZUtils.h                 |  12 +
 gfx/layers/apz/src/AsyncPanZoomController.cpp |  11 +-
 gfx/layers/apz/src/AsyncPanZoomController.h   |   4 +-
 gfx/layers/apz/src/HitTestingTreeNode.cpp     |  15 +-
 gfx/layers/apz/src/HitTestingTreeNode.h       |   4 +-
 gfx/layers/client/TextureClient.cpp           |   1 -
 gfx/layers/client/TiledContentClient.cpp      |  10 +-
 .../composite/AsyncCompositionManager.cpp     |  88 +++---
 .../composite/AsyncCompositionManager.h       |  17 +-
 .../composite/ContainerLayerComposite.cpp     |   4 +-
 gfx/layers/d3d11/TextureD3D11.cpp             |  12 +-
 gfx/layers/d3d9/DeviceManagerD3D9.cpp         |  34 +--
 gfx/layers/d3d9/TextureD3D9.cpp               |   8 +-
 gfx/layers/opengl/GrallocTextureClient.cpp    |   4 +-
 gfx/thebes/gfxWindowsPlatform.cpp             |   4 +-
 layout/base/ActiveLayerTracker.cpp            |  10 +-
 layout/base/FrameLayerBuilder.cpp             |  18 +-
 layout/base/FrameLayerBuilder.h               |   4 +-
 layout/base/FramePropertyTable.cpp            |  21 +-
 layout/base/FramePropertyTable.h              | 230 ++++++++++++----
 layout/base/RestyleManager.cpp                |   5 +-
 layout/base/RestyleTracker.h                  |   8 +-
 layout/base/UnitTransforms.h                  |  19 +-
 layout/base/Units.h                           |  24 ++
 layout/base/nsBidi.h                          |  14 +-
 layout/base/nsBidiPresUtils.cpp               |  30 +-
 layout/base/nsCSSFrameConstructor.cpp         |   8 +-
 layout/base/nsCSSRendering.cpp                | 214 ++++++++-------
 layout/base/nsCSSRendering.h                  |  40 +--
 layout/base/nsDisplayList.cpp                 |  69 +++--
 layout/base/nsDisplayList.h                   |   7 +-
 layout/base/nsLayoutUtils.cpp                 |  42 ++-
 layout/base/nsLayoutUtils.h                   |  11 +
 layout/forms/nsTextControlFrame.cpp           |   3 +-
 layout/forms/nsTextControlFrame.h             |  11 +-
 layout/generic/RubyUtils.cpp                  |  47 +++-
 layout/generic/RubyUtils.h                    |  48 ++++
 layout/generic/StickyScrollContainer.cpp      |   4 +-
 layout/generic/crashtests/1229437-1.html      |   8 +
 layout/generic/crashtests/1229437-2.html      |   5 +
 layout/generic/crashtests/crashtests.list     |   2 +
 layout/generic/nsBlockFrame.cpp               |  36 +--
 layout/generic/nsBlockFrame.h                 |   4 +-
 layout/generic/nsBulletFrame.cpp              |  17 +-
 layout/generic/nsCanvasFrame.cpp              |   7 +-
 layout/generic/nsCanvasFrame.h                |   4 +-
 layout/generic/nsContainerFrame.cpp           |  50 ++--
 layout/generic/nsContainerFrame.h             |  35 +--
 layout/generic/nsFlexContainerFrame.cpp       |   2 +-
 layout/generic/nsFloatManager.cpp             |   2 +-
 layout/generic/nsFontInflationData.cpp        |   4 +-
 layout/generic/nsFrame.cpp                    |  55 ++--
 layout/generic/nsGfxScrollFrame.cpp           |   2 +-
 layout/generic/nsGridContainerFrame.cpp       |   4 +-
 layout/generic/nsGridContainerFrame.h         |  18 +-
 layout/generic/nsHTMLReflowState.cpp          |   4 +-
 layout/generic/nsIFrame.h                     | 115 +++++---
 layout/generic/nsInlineFrame.cpp              |  13 +-
 layout/generic/nsRubyBaseContainerFrame.cpp   |  37 ++-
 layout/generic/nsRubyFrame.cpp                |  20 +-
 layout/generic/nsRubyFrame.h                  |   3 +-
 layout/generic/nsTextFrame.cpp                |  65 ++---
 layout/mathml/nsMathMLContainerFrame.cpp      |   8 +-
 layout/mathml/nsMathMLmtableFrame.cpp         |  14 +-
 layout/style/Declaration.cpp                  |  20 +-
 layout/style/StyleAnimationValue.cpp          |  30 +-
 layout/style/nsCSSParser.cpp                  | 189 ++++++-------
 layout/style/nsCSSPropList.h                  |  22 +-
 layout/style/nsCSSProps.cpp                   |  66 ++---
 layout/style/nsCSSProps.h                     |  12 +-
 layout/style/nsCSSValue.cpp                   |   4 +-
 layout/style/nsComputedDOMStyle.cpp           |  91 +++---
 layout/style/nsComputedDOMStyle.h             |  11 +-
 layout/style/nsRuleNode.cpp                   | 259 +++++++++---------
 layout/style/nsStyleConsts.h                  |  75 ++---
 layout/style/nsStyleSet.cpp                   |   4 +-
 layout/style/nsStyleStruct.cpp                | 253 +++++++++--------
 layout/style/nsStyleStruct.h                  | 114 +++++---
 layout/style/nsStyleUtil.cpp                  |   4 +-
 layout/svg/SVGTextFrame.cpp                   |   6 +-
 layout/svg/nsSVGEffects.cpp                   |  22 +-
 layout/svg/nsSVGEffects.h                     |  47 ++--
 layout/svg/nsSVGUtils.h                       |   8 +-
 layout/tables/nsTableFrame.cpp                |   8 +-
 layout/tables/nsTableFrame.h                  |   4 +-
 layout/tables/nsTablePainter.cpp              |   6 +-
 layout/tables/nsTableRowFrame.cpp             |   6 +-
 layout/tables/nsTableRowGroupFrame.cpp        |   7 +-
 layout/xul/nsMenuFrame.cpp                    |  13 +-
 mfbt/LinkedList.h                             |   7 +-
 mfbt/Poison.cpp                               |   4 +-
 mfbt/XorShift128PlusRNG.h                     |  24 +-
 netwerk/base/nsIChannel.idl                   |  11 +-
 .../passwordmgr/content/passwordManager.js    |  62 ++++-
 .../passwordmgr/content/passwordManager.xul   |  10 +-
 .../content/passwordManagerExceptions.xul     |   4 +-
 toolkit/components/passwordmgr/moz.build      |   3 +
 .../passwordmgr/test/browser/browser.ini      |   1 +
 .../browser/browser_passwordmgr_editing.js    | 126 +++++++++
 toolkit/components/telemetry/Histograms.json  |  52 +++-
 .../chrome/passwordmgr/passwordManager.dtd    |  11 +-
 .../chrome/passwordmgr/passwordmgr.properties |   2 -
 widget/TextEvents.h                           |  26 +-
 130 files changed, 2222 insertions(+), 1435 deletions(-)
 create mode 100644 dom/canvas/test/imagebitmap_bug1239300.js
 create mode 100644 layout/generic/crashtests/1229437-1.html
 create mode 100644 layout/generic/crashtests/1229437-2.html
 create mode 100644 toolkit/components/passwordmgr/test/browser/browser_passwordmgr_editing.js

diff --git a/accessible/windows/msaa/AccessibleWrap.cpp b/accessible/windows/msaa/AccessibleWrap.cpp
index 30969d688f..b159e23b29 100644
--- a/accessible/windows/msaa/AccessibleWrap.cpp
+++ b/accessible/windows/msaa/AccessibleWrap.cpp
@@ -838,7 +838,17 @@ AccessibleWrap::get_accSelection(VARIANT __RPC_FAR *pvarChildren)
 
   if (IsSelect()) {
     nsAutoTArray<Accessible*, 10> selectedItems;
-    SelectedItems(&selectedItems);
+    if (IsProxy()) {
+      nsTArray<ProxyAccessible*> proxies;
+      Proxy()->SelectedItems(&proxies);
+
+      uint32_t selectedCount = proxies.Length();
+      for (uint32_t i = 0; i < selectedCount; i++) {
+        selectedItems.AppendElement(WrapperFor(proxies[i]));
+      }
+    } else {
+      SelectedItems(&selectedItems);
+    }
 
     // 1) Create and initialize the enumeration
     RefPtr<AccessibleEnumerator> pEnum = new AccessibleEnumerator(selectedItems);
diff --git a/browser/components/preferences/security.xul b/browser/components/preferences/security.xul
index 43352b926c..95f2dfd991 100644
--- a/browser/components/preferences/security.xul
+++ b/browser/components/preferences/security.xul
@@ -93,11 +93,11 @@
 
     <!-- Passwords -->
     <groupbox id="passwordsGroup" orient="vertical">
-      <caption label="&passwords.label;"/>
+      <caption label="&logins.label;"/>
 
       <hbox id="savePasswordsBox">
         <checkbox id="savePasswords" flex="1"
-                  label="&rememberPasswords.label;" accesskey="&rememberPasswords.accesskey;"
+                  label="&rememberLogins.label;" accesskey="&rememberLogins.accesskey;"
                   preference="signon.rememberSignons"
                   onsyncfrompreference="return gSecurityPane.readSavePasswords();"/>
         <button id="passwordExceptions"
@@ -123,7 +123,7 @@
       <hbox id="showPasswordsBox">
         <spacer flex="1"/>
         <button id="showPasswords"
-                label="&savedPasswords.label;" accesskey="&savedPasswords.accesskey;"
+                label="&savedLogins.label;" accesskey="&savedLogins.accesskey;"
                 oncommand="gSecurityPane.showPasswords();"
                 preference="pref.privacy.disable_button.view_passwords"/>
       </hbox>
diff --git a/browser/locales/en-US/chrome/browser/preferences/security.dtd b/browser/locales/en-US/chrome/browser/preferences/security.dtd
index 2bd3b3aecf..9cf6b55c06 100644
--- a/browser/locales/en-US/chrome/browser/preferences/security.dtd
+++ b/browser/locales/en-US/chrome/browser/preferences/security.dtd
@@ -16,10 +16,10 @@
 <!ENTITY  addonSecurityLevel_High       "Medium: Block all harmful add-ons (default, recommended)">
 <!ENTITY  addonSecurityLevel_Extreme    "High: Block all add-ons with known issues">
 
-<!ENTITY  passwords.label               "Passwords">
+<!ENTITY  logins.label                  "Logins">
 
-<!ENTITY  rememberPasswords.label       "Remember passwords for sites">
-<!ENTITY  rememberPasswords.accesskey   "R">
+<!ENTITY  rememberLogins.label          "Remember logins for sites">
+<!ENTITY  rememberLogins.accesskey      "R">
 <!ENTITY  passwordExceptions.label      "Exceptions…">
 <!ENTITY  passwordExceptions.accesskey  "x">
 
@@ -31,8 +31,8 @@
 <!ENTITY  changeMasterPassword.label     "Change Master Password…">
 <!ENTITY  changeMasterPassword.accesskey "M">
 
-<!ENTITY  savedPasswords.label            "Saved Passwords…">
-<!ENTITY  savedPasswords.accesskey        "P">
+<!ENTITY  savedLogins.label              "Saved Logins…">
+<!ENTITY  savedLogins.accesskey          "L">
 
 <!ENTITY  SecProto.label             "Security Protocols">
 <!ENTITY  enableHSTS.label           "Enable Strict Transport Security (HSTS)">
diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index 91f69a0d69..2775b159d8 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -7710,7 +7710,7 @@ nsContentUtils::ToWidgetPoint(const CSSPoint& aPoint,
 {
   return LayoutDeviceIntPoint::FromAppUnitsRounded(
     (CSSPoint::ToAppUnits(aPoint) +
-    aOffset).ApplyResolution(aPresContext->PresShell()->GetCumulativeNonRootScaleResolution()),
+    aOffset).ApplyResolution(nsLayoutUtils::GetCurrentAPZResolutionScale(aPresContext->PresShell())),
     aPresContext->AppUnitsPerDevPixel());
 }
 
diff --git a/dom/base/nsDOMWindowUtils.cpp b/dom/base/nsDOMWindowUtils.cpp
index 28a066616c..dc519a23e8 100644
--- a/dom/base/nsDOMWindowUtils.cpp
+++ b/dom/base/nsDOMWindowUtils.cpp
@@ -481,7 +481,7 @@ nsDOMWindowUtils::SetDisplayPortBaseForElement(int32_t aX,
 NS_IMETHODIMP
 nsDOMWindowUtils::SetResolution(float aResolution)
 {
-  if (!nsContentUtils::IsCallerChrome()) {
+  if (!nsContentUtils::LegacyIsCallerChromeOrNativeCode()) {
     return NS_ERROR_DOM_SECURITY_ERR;
   }
 
@@ -542,7 +542,7 @@ nsDOMWindowUtils::GetIsResolutionSet(bool* aIsResolutionSet) {
 NS_IMETHODIMP
 nsDOMWindowUtils::SetIsFirstPaint(bool aIsFirstPaint)
 {
-  if (!nsContentUtils::IsCallerChrome()) {
+  if (!nsContentUtils::LegacyIsCallerChromeOrNativeCode()) {
     return NS_ERROR_DOM_SECURITY_ERR;
   }
 
@@ -557,7 +557,7 @@ nsDOMWindowUtils::SetIsFirstPaint(bool aIsFirstPaint)
 NS_IMETHODIMP
 nsDOMWindowUtils::GetIsFirstPaint(bool *aIsFirstPaint)
 {
-  if (!nsContentUtils::IsCallerChrome()) {
+  if (!nsContentUtils::LegacyIsCallerChromeOrNativeCode()) {
     return NS_ERROR_DOM_SECURITY_ERR;
   }
 
@@ -2443,8 +2443,10 @@ nsDOMWindowUtils::RestoreNormalRefresh()
     transaction->SendLeaveTestMode();
   }
 
-  nsRefreshDriver* driver = GetPresContext()->RefreshDriver();
-  driver->RestoreNormalRefresh();
+  if (nsPresContext* pc = GetPresContext()) {
+    nsRefreshDriver* driver = pc->RefreshDriver();
+    driver->RestoreNormalRefresh();
+  }
 
   return NS_OK;
 }
@@ -2944,7 +2946,7 @@ nsDOMWindowUtils::EnableDialogs()
 NS_IMETHODIMP
 nsDOMWindowUtils::DisableDialogs()
 {
-  if (!nsContentUtils::LegacyIsCallerChromeOrNativeCode()) {
+  if (!nsContentUtils::IsCallerChrome()) {
     return NS_ERROR_DOM_SECURITY_ERR;
   }
 
@@ -2958,7 +2960,7 @@ nsDOMWindowUtils::DisableDialogs()
 NS_IMETHODIMP
 nsDOMWindowUtils::AreDialogsEnabled(bool* aResult)
 {
-  if (!nsContentUtils::LegacyIsCallerChromeOrNativeCode()) {
+  if (!nsContentUtils::IsCallerChrome()) {
     return NS_ERROR_DOM_SECURITY_ERR;
   }
 
@@ -3691,7 +3693,7 @@ NS_IMETHODIMP
 nsDOMWindowUtils::SetHandlingUserInput(bool aHandlingUserInput,
                                        nsIJSRAIIHelper** aHelper)
 {
-  if (!nsContentUtils::LegacyIsCallerChromeOrNativeCode()) {
+  if (!nsContentUtils::IsCallerChrome()) {
     return NS_ERROR_DOM_SECURITY_ERR;
   }
 
diff --git a/dom/canvas/ImageBitmap.cpp b/dom/canvas/ImageBitmap.cpp
index 2c7c3d412a..6b6d7826b8 100644
--- a/dom/canvas/ImageBitmap.cpp
+++ b/dom/canvas/ImageBitmap.cpp
@@ -1065,7 +1065,7 @@ private:
     RefPtr<layers::Image> data = DecodeAndCropBlob(*mBlob, mCropRect);
 
     if (NS_WARN_IF(!data)) {
-      mPromise->MaybeReject(NS_ERROR_NOT_AVAILABLE);
+      mPromise->MaybeRejectWithNull();
       return nullptr;
     }
 
@@ -1143,9 +1143,9 @@ private:
       mPromise->MaybeReject(rv);
       return nullptr;
     }
-    
+
     if (NS_WARN_IF(!data)) {
-      mPromise->MaybeReject(NS_ERROR_NOT_AVAILABLE);
+      mPromise->MaybeRejectWithNull();
       return nullptr;
     }
 
diff --git a/dom/canvas/test/imagebitmap_bug1239300.js b/dom/canvas/test/imagebitmap_bug1239300.js
new file mode 100644
index 0000000000..16a77a9777
--- /dev/null
+++ b/dom/canvas/test/imagebitmap_bug1239300.js
@@ -0,0 +1,19 @@
+function testBug1239300() {
+  return new Promise(function(resolve, reject) {
+    createImageBitmap(new Blob()).then(
+      function() {
+        ok(false, "The promise should be rejected with null.");
+        reject();
+      },
+      function(result) {
+        if (result == null) {
+          ok(true, "The promise should be rejected with null.");
+          resolve();
+        } else {
+          ok(false, "The promise should be rejected with null.");
+          reject();
+        }
+      }
+    );
+  });
+}
\ No newline at end of file
diff --git a/dom/canvas/test/imagebitmap_on_worker.js b/dom/canvas/test/imagebitmap_on_worker.js
index 96a01e459f..be70467109 100644
--- a/dom/canvas/test/imagebitmap_on_worker.js
+++ b/dom/canvas/test/imagebitmap_on_worker.js
@@ -1,3 +1,5 @@
+importScripts("imagebitmap_bug1239300.js");
+
 function ok(expect, msg) {
   postMessage({type: "status", status: !!expect, msg: msg});
 }
@@ -77,5 +79,8 @@ onmessage = function(event) {
       promiseThrows(createImageBitmap(source), event.data.msg);
     }
     doneTask();
+  } else if (event.data.type == "testBug1239300") {
+    var promise = testBug1239300();
+    promise.then(doneTask, doneTask);
   }
 };
\ No newline at end of file
diff --git a/dom/canvas/test/mochitest.ini b/dom/canvas/test/mochitest.ini
index 5dd084905d..b1683bc6f2 100644
--- a/dom/canvas/test/mochitest.ini
+++ b/dom/canvas/test/mochitest.ini
@@ -24,6 +24,7 @@ support-files =
   image_transparent50.png
   image_yellow.png
   image_yellow75.png
+  imagebitmap_bug1239300.js
   imagebitmap_on_worker.js
   imagebitmap_structuredclone.js
   imagebitmap_structuredclone_iframe.html
@@ -247,13 +248,21 @@ support-files = captureStream_common.js
 support-files = file_drawWindow_source.html file_drawWindow_common.js
 skip-if = (buildapp == 'b2g' && toolkit != 'gonk')
 [test_imagebitmap.html]
+tags = imagebitmap
 [test_imagebitmap_close.html]
+tags = imagebitmap
 [test_imagebitmap_cropping.html]
+tags = imagebitmap
 [test_imagebitmap_on_worker.html]
+tags = imagebitmap
 [test_imagebitmap_structuredclone.html]
+tags = imagebitmap
 [test_imagebitmap_structuredclone_iframe.html]
+tags = imagebitmap
 [test_imagebitmap_structuredclone_window.html]
+tags = imagebitmap
 [test_imagebitmap_transfer.html]
+tags = imagebitmap
 [test_ImageData_ctor.html]
 [test_isPointInStroke.html]
 [test_mozDashOffset.html]
diff --git a/dom/canvas/test/test_imagebitmap.html b/dom/canvas/test/test_imagebitmap.html
index df9a2ec4af..9701159cbe 100644
--- a/dom/canvas/test/test_imagebitmap.html
+++ b/dom/canvas/test/test_imagebitmap.html
@@ -11,6 +11,7 @@
 <canvas id="c1" class="output" width="128" height="128"></canvas>
 <canvas id="c2" width="128" height="128"></canvas>
 
+<script src="imagebitmap_bug1239300.js"></script>
 <script type="text/javascript">
 
 SimpleTest.waitForExplicitFinish();
@@ -333,6 +334,7 @@ function runTests() {
     .then(testSources)
     .then(testExceptions)
     .then(testSecurityErrors)
+    .then(testBug1239300)
     .then(SimpleTest.finish, function(ev) { failed(ev); SimpleTest.finish(); });
 }
 
diff --git a/dom/canvas/test/test_imagebitmap_on_worker.html b/dom/canvas/test/test_imagebitmap_on_worker.html
index 3dbe0a638e..4eaad5bd46 100644
--- a/dom/canvas/test/test_imagebitmap_on_worker.html
+++ b/dom/canvas/test/test_imagebitmap_on_worker.html
@@ -130,6 +130,9 @@ function runTests() {
     xhr.send();
   }
   getNonImageFile("imagebitmap_on_worker.js");
+
+  // task: test bug : bug 1239300
+  WORKER_TASKS.tasks.push(new Task("testBug1239300"));
 }
 
 SimpleTest.waitForExplicitFinish();
diff --git a/dom/events/Event.cpp b/dom/events/Event.cpp
index 3dc88020d1..c2df00d9d8 100644
--- a/dom/events/Event.cpp
+++ b/dom/events/Event.cpp
@@ -933,7 +933,7 @@ Event::GetScreenCoords(nsPresContext* aPresContext,
     LayoutDevicePixel::ToAppUnits(aPoint, aPresContext->DeviceContext()->AppUnitsPerDevPixelAtUnitFullZoom());
 
   if (aPresContext->PresShell()) {
-    pt = pt.RemoveResolution(aPresContext->PresShell()->GetCumulativeNonRootScaleResolution());
+    pt = pt.RemoveResolution(nsLayoutUtils::GetCurrentAPZResolutionScale(aPresContext->PresShell()));
   }
 
   pt += LayoutDevicePixel::ToAppUnits(guiEvent->widget->WidgetToScreenOffset(),
diff --git a/dom/events/test/test_bug946632.html b/dom/events/test/test_bug946632.html
index 7e2154d34c..3ef7b815fd 100644
--- a/dom/events/test/test_bug946632.html
+++ b/dom/events/test/test_bug946632.html
@@ -37,12 +37,17 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=946632
 <script type="application/javascript">
 
 SimpleTest.waitForExplicitFinish();
-SimpleTest.waitForFocus(runTests, window);
+SimpleTest.waitForFocus(function() {
+  SpecialPowers.pushPrefEnv({
+    "set":[["general.smoothScroll", false],
+           ["mousewheel.system_scroll_override_on_root_content.enabled", false]]
+    }, runTests)
+  }, window);
 
 var input = document.querySelector("input");
 var container = document.querySelector("#container");
 
-function prepare(check)
+function reset()
 {
   container.scrollTop = 0;
   container.scrollLeft = 0;
@@ -50,6 +55,10 @@ function prepare(check)
   input.scrollLeft = 0;
   container.style.display='none';
   container.getBoundingClientRect();
+}
+
+function prepare(check)
+{
   container.style.display='';
   container.getBoundingClientRect();
   scrollHandler = function(event) {
@@ -70,9 +79,10 @@ var tests = [
       is(input.scrollTop, 0, "<input> horizontal line scroll input.scrollTop");
       is(input.scrollLeft, 0, "<input> horizontal line scroll input.scrollLeft");
     },
-    test: function() {
-      synthesizeWheel(input, 5, 5, { deltaMode: WheelEvent.DOM_DELTA_LINE,
-                                     deltaY: 1.0, lineOrPageDeltaY: 1 });
+    event: {
+      deltaMode: WheelEvent.DOM_DELTA_LINE,
+      deltaY: 1.0,
+      lineOrPageDeltaY: 1,
     }
   },
  { 
@@ -83,9 +93,10 @@ var tests = [
       is(container.scrollTop, 0, "<input> horizontal line scroll container.scrollTop");
       is(container.scrollLeft, 0, "<input> horizontal line scroll container.scrollLeft");
     },
-    test: function() {
-      synthesizeWheel(input, 5, 5, { deltaMode: WheelEvent.DOM_DELTA_LINE,
-                                     deltaX: 1.0, lineOrPageDeltaX: 1 });
+    event: {
+      deltaMode: WheelEvent.DOM_DELTA_LINE,
+      deltaX: 1.0,
+      lineOrPageDeltaX: 1
     }
   },
  { 
@@ -96,9 +107,10 @@ var tests = [
       is(input.scrollTop, 0, "<input> vertical page scroll input.scrollTop");
       is(input.scrollLeft, 0, "<input> vertical page scroll input.scrollLeft");
     },
-    test: function() {
-      synthesizeWheel(input, 5, 5, { deltaMode: WheelEvent.DOM_DELTA_PAGE,
-                                     deltaY: 1.0, lineOrPageDeltaY: 1 });
+    event: {
+      deltaMode: WheelEvent.DOM_DELTA_PAGE,
+      deltaY: 1.0,
+      lineOrPageDeltaY: 1
     }
   },
  { 
@@ -109,9 +121,10 @@ var tests = [
       is(container.scrollTop, 0, "<input> horizontal page scroll container.scrollTop");
       is(container.scrollLeft, 0, "<input> horizontal page scroll container.scrollLeft");
     },
-    test: function() {
-      synthesizeWheel(input, 5, 5, { deltaMode: WheelEvent.DOM_DELTA_PAGE,
-                                     deltaX: 1.0, lineOrPageDeltaX: 1 });
+    event: {
+      deltaMode: WheelEvent.DOM_DELTA_PAGE,
+      deltaX: 1.0,
+      lineOrPageDeltaX: 1
     }
   },
 ];
@@ -120,15 +133,20 @@ var i = 0;
 function nextTest()
 {
   if (i == tests.length) {
+    SpecialPowers.DOMWindowUtils.restoreNormalRefresh();
     SimpleTest.finish();
     return;
   }
   var test = tests[i];
   ++i;
-  prepare(test.check);
+  reset();
 
   window.waitForAllPaintsFlushed(function() {
-    test.test();
+    prepare(test.check);
+
+    sendWheelAndPaint(input, 5, 5, test.event, function() {
+      // Do nothing - we wait for the scroll event.
+    });
   });
 }
 
diff --git a/dom/promise/Promise.cpp b/dom/promise/Promise.cpp
index b6a8c66000..19e1d8ba1c 100644
--- a/dom/promise/Promise.cpp
+++ b/dom/promise/Promise.cpp
@@ -906,6 +906,12 @@ Promise::MaybeReject(const RefPtr<MediaStreamError>& aArg) {
   MaybeSomething(aArg, &Promise::MaybeReject);
 }
 
+void
+Promise::MaybeRejectWithNull()
+{
+  MaybeSomething(JS::NullHandleValue, &Promise::MaybeReject);
+}
+
 bool
 Promise::PerformMicroTaskCheckpoint()
 {
@@ -2364,7 +2370,7 @@ void
 Promise::AppendCallbacks(PromiseCallback* aResolveCallback,
                          PromiseCallback* aRejectCallback)
 {
-  if (mGlobal->IsDying()) {
+  if (!mGlobal || mGlobal->IsDying()) {
     return;
   }
 
diff --git a/dom/promise/Promise.h b/dom/promise/Promise.h
index 00b6b2494e..a2d0846bec 100644
--- a/dom/promise/Promise.h
+++ b/dom/promise/Promise.h
@@ -148,6 +148,8 @@ public:
 
   void MaybeReject(const RefPtr<MediaStreamError>& aArg);
 
+  void MaybeRejectWithNull();
+
   // DO NOT USE MaybeRejectBrokenly with in new code.  Promises should be
   // rejected with Error instances.
   // Note: MaybeRejectBrokenly is a template so we can use it with DOMError
diff --git a/gfx/2d/DrawTargetD2D1.cpp b/gfx/2d/DrawTargetD2D1.cpp
index 96fa80e452..1197f9b5bf 100644
--- a/gfx/2d/DrawTargetD2D1.cpp
+++ b/gfx/2d/DrawTargetD2D1.cpp
@@ -951,7 +951,7 @@ DrawTargetD2D1::Init(ID3D11Texture2D* aTexture, SurfaceFormat aFormat)
   hr = mDC->CreateSolidColorBrush(D2D1::ColorF(0, 0), getter_AddRefs(mSolidColorBrush));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << "[D2D1.1] Failure creating solid color brush.";
+    gfxCriticalError() << "[D2D1.1] Failure creating solid color brush (I1).";
     return false;
   }
 
@@ -1006,7 +1006,7 @@ DrawTargetD2D1::Init(const IntSize &aSize, SurfaceFormat aFormat)
   hr = mDC->CreateSolidColorBrush(D2D1::ColorF(0, 0), getter_AddRefs(mSolidColorBrush));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << "[D2D1.1] Failure creating solid color brush.";
+    gfxCriticalError() << "[D2D1.1] Failure creating solid color brush (I2).";
     return false;
   }
 
diff --git a/gfx/2d/Factory.cpp b/gfx/2d/Factory.cpp
index 75c43396d0..d7faefc196 100644
--- a/gfx/2d/Factory.cpp
+++ b/gfx/2d/Factory.cpp
@@ -319,7 +319,7 @@ already_AddRefed<DrawTarget>
 Factory::CreateDrawTarget(BackendType aBackend, const IntSize &aSize, SurfaceFormat aFormat)
 {
   if (!AllowedSurfaceSize(aSize)) {
-    gfxCriticalError(LoggerOptionsBasedOnSize(aSize)) << "Failed to allocate a surface due to invalid size " << aSize;
+    gfxCriticalError(LoggerOptionsBasedOnSize(aSize)) << "Failed to allocate a surface due to invalid size (CDT) " << aSize;
     return nullptr;
   }
 
@@ -410,7 +410,7 @@ Factory::CreateDrawTargetForData(BackendType aBackend,
 {
   MOZ_ASSERT(aData);
   if (!AllowedSurfaceSize(aSize)) {
-    gfxCriticalError(LoggerOptionsBasedOnSize(aSize)) << "Failed to allocate a surface due to invalid size " << aSize;
+    gfxCriticalError(LoggerOptionsBasedOnSize(aSize)) << "Failed to allocate a surface due to invalid size (DTD) " << aSize;
     return nullptr;
   }
 
@@ -926,7 +926,7 @@ Factory::CreateDataSourceSurface(const IntSize &aSize,
                                  bool aZero)
 {
   if (!AllowedSurfaceSize(aSize)) {
-    gfxCriticalError(LoggerOptionsBasedOnSize(aSize)) << "Failed to allocate a surface due to invalid size " << aSize;
+    gfxCriticalError(LoggerOptionsBasedOnSize(aSize)) << "Failed to allocate a surface due to invalid size (DSS) " << aSize;
     return nullptr;
   }
 
diff --git a/gfx/2d/SourceSurfaceD2D1.cpp b/gfx/2d/SourceSurfaceD2D1.cpp
index 0d4b287c4f..8f67970a4f 100644
--- a/gfx/2d/SourceSurfaceD2D1.cpp
+++ b/gfx/2d/SourceSurfaceD2D1.cpp
@@ -195,7 +195,7 @@ DataSourceSurfaceD2D1::Map(MapType aMapType, MappedSurface *aMappedSurface)
 
   D2D1_MAPPED_RECT map;
   if (FAILED(mBitmap->Map(D2D1_MAP_OPTIONS_READ, &map))) {
-    gfxCriticalError() << "Failed to map bitmap.";
+    gfxCriticalError() << "Failed to map bitmap (M).";
     return false;
   }
   aMappedSurface->mData = map.bits;
@@ -231,7 +231,7 @@ DataSourceSurfaceD2D1::EnsureMapped()
     return;
   }
   if (FAILED(mBitmap->Map(D2D1_MAP_OPTIONS_READ, &mMap))) {
-    gfxCriticalError() << "Failed to map bitmap.";
+    gfxCriticalError() << "Failed to map bitmap (EM).";
     return;
   }
   mMapped = true;
diff --git a/gfx/2d/SourceSurfaceD2DTarget.cpp b/gfx/2d/SourceSurfaceD2DTarget.cpp
index e0009e73bb..464a64f423 100644
--- a/gfx/2d/SourceSurfaceD2DTarget.cpp
+++ b/gfx/2d/SourceSurfaceD2DTarget.cpp
@@ -65,7 +65,7 @@ SourceSurfaceD2DTarget::GetDataSurface()
   desc.MiscFlags = 0;
 
   if (!Factory::GetDirect3D10Device()) {
-    gfxCriticalError() << "Invalid D3D10 device in D2D target surface";
+    gfxCriticalError() << "Invalid D3D10 device in D2D target surface (GDS)";
     return nullptr;
   }
 
@@ -97,7 +97,7 @@ SourceSurfaceD2DTarget::GetSRView()
   }
 
   if (!Factory::GetDirect3D10Device()) {
-    gfxCriticalError() << "Invalid D3D10 device in D2D target surface";
+    gfxCriticalError() << "Invalid D3D10 device in D2D target surface (SRV)";
     return nullptr;
   }
 
diff --git a/gfx/layers/BufferTexture.cpp b/gfx/layers/BufferTexture.cpp
index 1448695762..5b48647a17 100644
--- a/gfx/layers/BufferTexture.cpp
+++ b/gfx/layers/BufferTexture.cpp
@@ -303,19 +303,19 @@ BufferTextureData::UpdateFromSurface(gfx::SourceSurface* aSurface)
   RefPtr<gfx::DataSourceSurface> srcSurf = aSurface->GetDataSurface();
 
   if (!srcSurf) {
-    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface.";
+    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface (BT).";
     return false;
   }
 
   if (surface->GetSize() != srcSurf->GetSize() || surface->GetFormat() != srcSurf->GetFormat()) {
-    gfxCriticalError() << "Attempt to update texture client from a surface with a different size or format! This: " << surface->GetSize() << " " << surface->GetFormat() << " Other: " << aSurface->GetSize() << " " << aSurface->GetFormat();
+    gfxCriticalError() << "Attempt to update texture client from a surface with a different size or format (BT)! This: " << surface->GetSize() << " " << surface->GetFormat() << " Other: " << aSurface->GetSize() << " " << aSurface->GetFormat();
     return false;
   }
 
   gfx::DataSourceSurface::MappedSurface sourceMap;
   gfx::DataSourceSurface::MappedSurface destMap;
   if (!srcSurf->Map(gfx::DataSourceSurface::READ, &sourceMap)) {
-    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface.";
+    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface (BT).";
     return false;
   }
 
diff --git a/gfx/layers/LayerMetricsWrapper.h b/gfx/layers/LayerMetricsWrapper.h
index 7a5ca6a002..fbda790f07 100644
--- a/gfx/layers/LayerMetricsWrapper.h
+++ b/gfx/layers/LayerMetricsWrapper.h
@@ -7,6 +7,7 @@
 #define GFX_LAYERMETRICSWRAPPER_H
 
 #include "Layers.h"
+#include "UnitTransforms.h"
 
 namespace mozilla {
 namespace layers {
@@ -299,6 +300,11 @@ public:
     return gfx::Matrix4x4();
   }
 
+  CSSTransformMatrix GetTransformTyped() const
+  {
+    return ViewAs<CSSTransformMatrix>(GetTransform());
+  }
+
   bool TransformIsPerspective() const
   {
     MOZ_ASSERT(IsValid());
diff --git a/gfx/layers/Layers.cpp b/gfx/layers/Layers.cpp
index af81384fec..c9fbcc120e 100644
--- a/gfx/layers/Layers.cpp
+++ b/gfx/layers/Layers.cpp
@@ -892,6 +892,12 @@ Layer::GetTransform() const
   return transform;
 }
 
+const CSSTransformMatrix
+Layer::GetTransformTyped() const
+{
+  return ViewAs<CSSTransformMatrix>(GetTransform());
+}
+
 const Matrix4x4
 Layer::GetLocalTransform()
 {
@@ -909,6 +915,12 @@ Layer::GetLocalTransform()
   return transform;
 }
 
+const LayerToParentLayerMatrix4x4
+Layer::GetLocalTransformTyped()
+{
+  return ViewAs<LayerToParentLayerMatrix4x4>(GetLocalTransform());
+}
+
 bool
 Layer::HasTransformAnimation() const
 {
diff --git a/gfx/layers/Layers.h b/gfx/layers/Layers.h
index 4dc260a5f4..0c4b19a65c 100644
--- a/gfx/layers/Layers.h
+++ b/gfx/layers/Layers.h
@@ -1278,6 +1278,9 @@ public:
   virtual Layer* GetFirstChild() const { return nullptr; }
   virtual Layer* GetLastChild() const { return nullptr; }
   const gfx::Matrix4x4 GetTransform() const;
+  // Same as GetTransform(), but returns the transform as a strongly-typed
+  // matrix. Eventually this will replace GetTransform().
+  const CSSTransformMatrix GetTransformTyped() const;
   const gfx::Matrix4x4& GetBaseTransform() const { return mTransform; }
   // Note: these are virtual because ContainerLayerComposite overrides them.
   virtual float GetPostXScale() const { return mPostXScale; }
@@ -1348,10 +1351,17 @@ public:
 
   /**
    * Returns the local transform for this layer: either mTransform or,
-   * for shadow layers, GetShadowTransform()
+   * for shadow layers, GetShadowTransform(), in either case with the
+   * pre- and post-scales applied.
    */
   const gfx::Matrix4x4 GetLocalTransform();
 
+  /**
+   * Same as GetLocalTransform(), but returns a strongly-typed matrix.
+   * Eventually, this will replace GetLocalTransform().
+   */
+  const LayerToParentLayerMatrix4x4 GetLocalTransformTyped();
+
   /**
    * Returns the local opacity for this layer: either mOpacity or,
    * for shadow layers, GetShadowOpacity()
diff --git a/gfx/layers/LayersTypes.h b/gfx/layers/LayersTypes.h
index 616130dfbc..0feed84356 100644
--- a/gfx/layers/LayersTypes.h
+++ b/gfx/layers/LayersTypes.h
@@ -13,6 +13,7 @@
 #include "mozilla/layers/GonkNativeHandle.h"
 #endif
 
+#include "Units.h"
 #include "mozilla/gfx/Point.h"          // for IntPoint
 #include "mozilla/TypedEnumBits.h"
 #include "nsRegion.h"
@@ -284,6 +285,22 @@ enum TextureDumpMode {
   DoNotCompress  // dump texture uncompressed
 };
 
+// Some specialized typedefs of Matrix4x4Typed.
+typedef gfx::Matrix4x4Typed<LayerPixel, CSSTransformedLayerPixel> CSSTransformMatrix;
+// Several different async transforms can contribute to a layer's transform
+// (specifically, an async animation can contribute a transform, and each APZC
+// that scrolls a layer can contribute async scroll/zoom and overscroll
+// transforms).
+// To try to model this with typed units, we represent individual async
+// transforms as ParentLayer -> ParentLayer transforms (aliased as
+// AsyncTransformComponentMatrix), and we represent the product of all of them
+// as a CSSTransformLayer -> ParentLayer transform (aliased as
+// AsyncTransformMatrix). To create an AsyncTransformMatrix from component
+// matrices, a ViewAs operation is needed. A MultipleAsyncTransforms
+// PixelCastJustification is provided for this purpose.
+typedef gfx::Matrix4x4Typed<ParentLayerPixel, ParentLayerPixel> AsyncTransformComponentMatrix;
+typedef gfx::Matrix4x4Typed<CSSTransformedLayerPixel, ParentLayerPixel> AsyncTransformMatrix;
+
 } // namespace layers
 } // namespace mozilla
 
diff --git a/gfx/layers/TextureDIB.cpp b/gfx/layers/TextureDIB.cpp
index d021cfa2e9..7c825da3a3 100644
--- a/gfx/layers/TextureDIB.cpp
+++ b/gfx/layers/TextureDIB.cpp
@@ -28,6 +28,8 @@ public:
                 TextureFlags aFlags = TextureFlags::DEFAULT,
                 TextureAllocationFlags aAllocFlags = ALLOC_DEFAULT) const override;
 
+  virtual bool UpdateFromSurface(gfx::SourceSurface* aSurface) override;
+
   static
   DIBTextureData* Create(gfx::IntSize aSize, gfx::SurfaceFormat aFormat);
 
@@ -63,6 +65,8 @@ public:
                 TextureFlags aFlags = TextureFlags::DEFAULT,
                 TextureAllocationFlags aAllocFlags = ALLOC_DEFAULT) const override;
 
+  virtual bool UpdateFromSurface(gfx::SourceSurface* aSurface) override;
+
   static
   DIBTextureData* Create(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
                          ISurfaceAllocator* aAllocator);
@@ -101,6 +105,10 @@ public:
   virtual ~ShmemDIBTextureData() 
   {
     MOZ_COUNT_DTOR(ShmemDIBTextureData);
+
+    // The host side has its own references and handles to this data, we can
+    // safely clear ours.
+    DeallocateData();
   }
 
   HANDLE mFileMapping;
@@ -115,31 +123,6 @@ DIBTextureData::BorrowDrawTarget()
   return gfxPlatform::GetPlatform()->CreateDrawTargetForSurface(mSurface, mSize);
 }
 
-bool
-DIBTextureData::UpdateFromSurface(gfx::SourceSurface* aSurface)
-{
-  RefPtr<gfxImageSurface> imgSurf = mSurface->GetAsImageSurface();
-
-  RefPtr<DataSourceSurface> srcSurf = aSurface->GetDataSurface();
-
-  if (!srcSurf) {
-    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface.";
-    return false;
-  }
-
-  DataSourceSurface::MappedSurface sourceMap;
-  srcSurf->Map(DataSourceSurface::READ, &sourceMap);
-
-  for (int y = 0; y < srcSurf->GetSize().height; y++) {
-    memcpy(imgSurf->Data() + imgSurf->Stride() * y,
-           sourceMap.mData + sourceMap.mStride * y,
-           srcSurf->GetSize().width * BytesPerPixel(srcSurf->GetFormat()));
-  }
-
-  srcSurf->Unmap();
-  return true;
-}
-
 DIBTextureData*
 DIBTextureData::Create(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
                        ISurfaceAllocator* aAllocator)
@@ -192,6 +175,34 @@ MemoryDIBTextureData::Create(gfx::IntSize aSize, gfx::SurfaceFormat aFormat)
   return new MemoryDIBTextureData(aSize, aFormat, surface);
 }
 
+bool
+MemoryDIBTextureData::UpdateFromSurface(gfx::SourceSurface* aSurface)
+{
+  RefPtr<gfxImageSurface> imgSurf = mSurface->GetAsImageSurface();
+
+  RefPtr<DataSourceSurface> srcSurf = aSurface->GetDataSurface();
+
+  if (!srcSurf) {
+    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface (DIB).";
+    return false;
+  }
+
+  DataSourceSurface::MappedSurface sourceMap;
+  if (!srcSurf->Map(gfx::DataSourceSurface::READ, &sourceMap)) {
+    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface.";
+    return false;
+  }
+
+  for (int y = 0; y < srcSurf->GetSize().height; y++) {
+    memcpy(imgSurf->Data() + imgSurf->Stride() * y,
+           sourceMap.mData + sourceMap.mStride * y,
+           srcSurf->GetSize().width * BytesPerPixel(srcSurf->GetFormat()));
+  }
+
+  srcSurf->Unmap();
+  return true;
+}
+
 TextureData*
 ShmemDIBTextureData::CreateSimilar(ISurfaceAllocator* aAllocator,
                                    TextureFlags aFlags,
@@ -203,6 +214,46 @@ ShmemDIBTextureData::CreateSimilar(ISurfaceAllocator* aAllocator,
   return ShmemDIBTextureData::Create(mSize, mFormat, aAllocator);
 }
 
+bool
+ShmemDIBTextureData::UpdateFromSurface(gfx::SourceSurface* aSurface)
+{
+
+  RefPtr<DataSourceSurface> srcSurf = aSurface->GetDataSurface();
+
+  if (!srcSurf) {
+    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface (DTD).";
+    return false;
+  }
+
+  DataSourceSurface::MappedSurface sourceMap;
+  if (!srcSurf->Map(gfx::DataSourceSurface::READ, &sourceMap)) {
+    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface.";
+    return false;
+  }
+
+  GdiFlush();
+
+  uint32_t stride = mSize.width * BytesPerPixel(mFormat);
+  uint8_t* data = (uint8_t*)::MapViewOfFile(mFileMapping, FILE_MAP_WRITE, 0, 0, stride * mSize.height);
+
+  if (!data) {
+    gfxCriticalError() << "Failed to map view of file for UpdateFromSurface.";
+    srcSurf->Unmap();
+    return false;
+  }
+
+  for (int y = 0; y < srcSurf->GetSize().height; y++) {
+    memcpy(data + stride * y,
+           sourceMap.mData + sourceMap.mStride * y,
+           srcSurf->GetSize().width * BytesPerPixel(srcSurf->GetFormat()));
+  }
+
+  ::UnmapViewOfFile(data);
+
+  srcSurf->Unmap();
+  return true;
+}
+
 bool
 ShmemDIBTextureData::Serialize(SurfaceDescriptor& aOutDescriptor)
 {
@@ -229,14 +280,6 @@ ShmemDIBTextureData::Create(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
     return nullptr;
   }
 
-  uint8_t* data = (uint8_t*)::MapViewOfFile(fileMapping, FILE_MAP_WRITE | FILE_MAP_READ,
-                                            0, 0, aSize.width * aSize.height
-                                                  * BytesPerPixel(aFormat));
-
-  memset(data, 0x80, aSize.width * aSize.height * BytesPerPixel(aFormat));
-
-  ::UnmapViewOfFile(fileMapping);
-
   BITMAPV4HEADER header;
   memset(&header, 0, sizeof(BITMAPV4HEADER));
   header.bV4Size          = sizeof(BITMAPV4HEADER);
@@ -249,7 +292,11 @@ ShmemDIBTextureData::Create(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
   header.bV4GreenMask     = 0x0000FF00;
   header.bV4BlueMask      = 0x000000FF;
 
-  HDC dc = ::CreateCompatibleDC(::GetDC(NULL));
+  HDC nulldc = ::GetDC(NULL);
+
+  HDC dc = ::CreateCompatibleDC(nulldc);
+
+  ::ReleaseDC(nullptr, nulldc);
 
   if (!dc) {
     ::CloseHandle(fileMapping);
@@ -264,7 +311,7 @@ ShmemDIBTextureData::Create(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
 
   if (!bitmap) {
     gfxCriticalError() << "Failed to create DIB section for a bitmap of size "
-                       << aSize;
+                       << aSize << " and mapSize " << mapSize;
     ::CloseHandle(fileMapping);
     ::DeleteDC(dc);
     return nullptr;
@@ -392,6 +439,14 @@ TextureHostFileMapping::~TextureHostFileMapping()
   ::CloseHandle(mFileMapping);
 }
 
+UserDataKey kFileMappingKey;
+
+static void UnmapFileData(void* aData)
+{
+  MOZ_ASSERT(aData);
+  ::UnmapViewOfFile(aData);
+}
+
 void
 TextureHostFileMapping::UpdatedInternal(const nsIntRegion* aRegion)
 {
@@ -410,14 +465,14 @@ TextureHostFileMapping::UpdatedInternal(const nsIntRegion* aRegion)
   if (data) {
     RefPtr<DataSourceSurface> surf = Factory::CreateWrappingDataSourceSurface(data, mSize.width * BytesPerPixel(mFormat), mSize, mFormat);
 
+    surf->AddUserData(&kFileMappingKey, data, UnmapFileData);
+
     if (!mTextureSource->Update(surf, const_cast<nsIntRegion*>(aRegion))) {
       mTextureSource = nullptr;
     }
   } else {
     mTextureSource = nullptr;
   }
-
-  ::UnmapViewOfFile(data);
 }
 
 }
diff --git a/gfx/layers/TextureDIB.h b/gfx/layers/TextureDIB.h
index 9f42f900d5..6e340f2150 100644
--- a/gfx/layers/TextureDIB.h
+++ b/gfx/layers/TextureDIB.h
@@ -30,8 +30,6 @@ public:
 
   virtual already_AddRefed<gfx::DrawTarget> BorrowDrawTarget() override;
 
-  virtual bool UpdateFromSurface(gfx::SourceSurface* aSurface) override;
-
   virtual bool HasInternalBuffer() const override { return true; }
 
   static
diff --git a/gfx/layers/apz/src/APZCTreeManager.cpp b/gfx/layers/apz/src/APZCTreeManager.cpp
index 66e6e97285..81ec7c33b5 100644
--- a/gfx/layers/apz/src/APZCTreeManager.cpp
+++ b/gfx/layers/apz/src/APZCTreeManager.cpp
@@ -358,7 +358,9 @@ APZCTreeManager::PrepareNodeForLayer(const LayerMetricsWrapper& aLayer,
   if (!needsApzc) {
     node = RecycleOrCreateNode(aState, nullptr, aLayersId);
     AttachNodeToTree(node, aParent, aNextSibling);
-    node->SetHitTestData(GetEventRegions(aLayer), aLayer.GetTransform(),
+    node->SetHitTestData(
+        GetEventRegions(aLayer),
+        aLayer.GetTransformTyped(),
         aLayer.GetClipRect() ? Some(ParentLayerIntRegion(*aLayer.GetClipRect())) : Nothing(),
         GetEventRegionsOverride(aParent, aLayer));
     node->SetScrollbarData(aLayer.GetScrollbarTargetContainerId(),
@@ -462,7 +464,10 @@ APZCTreeManager::PrepareNodeForLayer(const LayerMetricsWrapper& aLayer,
     MOZ_ASSERT(node->IsPrimaryHolder() && node->GetApzc() && node->GetApzc()->Matches(guid));
 
     ParentLayerIntRegion clipRegion = ComputeClipRegion(state->mController, aLayer);
-    node->SetHitTestData(GetEventRegions(aLayer), aLayer.GetTransform(), Some(clipRegion),
+    node->SetHitTestData(
+        GetEventRegions(aLayer),
+        aLayer.GetTransformTyped(),
+        Some(clipRegion),
         GetEventRegionsOverride(aParent, aLayer));
     apzc->SetAncestorTransform(aAncestorTransform);
 
@@ -516,11 +521,20 @@ APZCTreeManager::PrepareNodeForLayer(const LayerMetricsWrapper& aLayer,
     // Even though different layers associated with a given APZC may be at
     // different levels in the layer tree (e.g. one being an uncle of another),
     // we require from Layout that the CSS transforms up to their common
-    // ancestor be the same.
-    MOZ_ASSERT(aAncestorTransform == apzc->GetAncestorTransform());
+    // ancestor be roughly the same. There are cases in which the transforms
+    // are not exactly the same, for example if the parent is container layer
+    // for an opacity, and this container layer has a resolution-induced scale
+    // as its base transform and a prescale that is supposed to undo that scale.
+    // Due to floating point inaccuracies those transforms can end up not quite
+    // canceling each other. That's why we're using a fuzzy comparison here
+    // instead of an exact one.
+    MOZ_ASSERT(aAncestorTransform.FuzzyEqualsMultiplicative(apzc->GetAncestorTransform()));
 
     ParentLayerIntRegion clipRegion = ComputeClipRegion(state->mController, aLayer);
-    node->SetHitTestData(GetEventRegions(aLayer), aLayer.GetTransform(), Some(clipRegion),
+    node->SetHitTestData(
+        GetEventRegions(aLayer),
+        aLayer.GetTransformTyped(),
+        Some(clipRegion),
         GetEventRegionsOverride(aParent, aLayer));
   }
 
@@ -1844,7 +1858,7 @@ APZCTreeManager::GetScreenToApzcTransform(const AsyncPanZoomController *aApzc) c
     // ancestorUntransform is updated to RC.Inverse() * QC.Inverse() when parent == P
     ancestorUntransform = parent->GetAncestorTransform().Inverse();
     // asyncUntransform is updated to PA.Inverse() when parent == P
-    Matrix4x4 asyncUntransform = parent->GetCurrentAsyncTransformWithOverscroll().Inverse();
+    Matrix4x4 asyncUntransform = parent->GetCurrentAsyncTransformWithOverscroll().Inverse().ToUnknownMatrix();
     // untransformSinceLastApzc is RC.Inverse() * QC.Inverse() * PA.Inverse()
     Matrix4x4 untransformSinceLastApzc = ancestorUntransform * asyncUntransform;
 
@@ -1876,7 +1890,7 @@ APZCTreeManager::GetApzcToGeckoTransform(const AsyncPanZoomController *aApzc) co
   // leftmost matrix in a multiplication is applied first.
 
   // asyncUntransform is LA.Inverse()
-  Matrix4x4 asyncUntransform = aApzc->GetCurrentAsyncTransformWithOverscroll().Inverse();
+  Matrix4x4 asyncUntransform = aApzc->GetCurrentAsyncTransformWithOverscroll().Inverse().ToUnknownMatrix();
 
   // aTransformToGeckoOut is initialized to LA.Inverse() * LD * MC * NC * OC * PC
   result = asyncUntransform * aApzc->GetTransformToLastDispatchedPaint() * aApzc->GetAncestorTransform();
diff --git a/gfx/layers/apz/src/APZUtils.h b/gfx/layers/apz/src/APZUtils.h
index a85fddc03e..75565ca067 100644
--- a/gfx/layers/apz/src/APZUtils.h
+++ b/gfx/layers/apz/src/APZUtils.h
@@ -8,6 +8,8 @@
 #define mozilla_layers_APZUtils_h
 
 #include <stdint.h>                     // for uint32_t
+#include "LayersTypes.h"
+#include "UnitTransforms.h"
 #include "mozilla/gfx/Point.h"
 #include "mozilla/FloatingPoint.h"
 
@@ -61,6 +63,16 @@ static bool IsZero(const gfx::PointTyped<Units>& aPoint)
       && FuzzyEqualsAdditive(aPoint.y, 0.0f, COORDINATE_EPSILON);
 }
 
+// Deem an AsyncTransformComponentMatrix (obtained by multiplying together
+// one or more AsyncTransformComponentMatrix objects) as constituting a
+// complete async transform.
+inline AsyncTransformMatrix
+CompleteAsyncTransform(const AsyncTransformComponentMatrix& aMatrix)
+{
+  return ViewAs<AsyncTransformMatrix>(aMatrix,
+      PixelCastJustification::MultipleAsyncTransforms);
+}
+
 } // namespace layers
 } // namespace mozilla
 
diff --git a/gfx/layers/apz/src/AsyncPanZoomController.cpp b/gfx/layers/apz/src/AsyncPanZoomController.cpp
index 3e04f1b180..e75a44e88b 100644
--- a/gfx/layers/apz/src/AsyncPanZoomController.cpp
+++ b/gfx/layers/apz/src/AsyncPanZoomController.cpp
@@ -2896,10 +2896,10 @@ bool AsyncPanZoomController::UpdateAnimation(const TimeStamp& aSampleTime,
   return false;
 }
 
-Matrix4x4 AsyncPanZoomController::GetOverscrollTransform() const {
+AsyncTransformComponentMatrix AsyncPanZoomController::GetOverscrollTransform() const {
   ReentrantMonitorAutoEnter lock(mMonitor);
   if (!IsOverscrolled()) {
-    return Matrix4x4();
+    return AsyncTransformComponentMatrix();
   }
 
   // The overscroll effect is a uniform stretch along the overscrolled axis,
@@ -2936,7 +2936,7 @@ Matrix4x4 AsyncPanZoomController::GetOverscrollTransform() const {
   }
 
   // Combine the transformations into a matrix.
-  return Matrix4x4::Scaling(scaleX, scaleY, 1)
+  return AsyncTransformComponentMatrix::Scaling(scaleX, scaleY, 1)
                     .PostTranslate(translation.x, translation.y, 0);
 }
 
@@ -3033,8 +3033,9 @@ AsyncTransform AsyncPanZoomController::GetCurrentAsyncTransform() const {
     -translation);
 }
 
-Matrix4x4 AsyncPanZoomController::GetCurrentAsyncTransformWithOverscroll() const {
-  return Matrix4x4(GetCurrentAsyncTransform()) * GetOverscrollTransform();
+AsyncTransformComponentMatrix AsyncPanZoomController::GetCurrentAsyncTransformWithOverscroll() const {
+  return AsyncTransformComponentMatrix(GetCurrentAsyncTransform())
+       * GetOverscrollTransform();
 }
 
 Matrix4x4 AsyncPanZoomController::GetTransformToLastDispatchedPaint() const {
diff --git a/gfx/layers/apz/src/AsyncPanZoomController.h b/gfx/layers/apz/src/AsyncPanZoomController.h
index ecfa84e8ca..3cf998773f 100644
--- a/gfx/layers/apz/src/AsyncPanZoomController.h
+++ b/gfx/layers/apz/src/AsyncPanZoomController.h
@@ -174,7 +174,7 @@ public:
    * Return a visual effect that reflects this apzc's
    * overscrolled state, if any.
    */
-  Matrix4x4 GetOverscrollTransform() const;
+  AsyncTransformComponentMatrix GetOverscrollTransform() const;
 
   /**
    * A shadow layer update has arrived. |aLayerMetrics| is the new FrameMetrics
@@ -226,7 +226,7 @@ public:
    * Returns the same transform as GetCurrentAsyncTransform(), but includes
    * any transform due to axis over-scroll.
    */
-  Matrix4x4 GetCurrentAsyncTransformWithOverscroll() const;
+  AsyncTransformComponentMatrix GetCurrentAsyncTransformWithOverscroll() const;
 
   /**
    * Returns the transform to take something from the coordinate space of the
diff --git a/gfx/layers/apz/src/HitTestingTreeNode.cpp b/gfx/layers/apz/src/HitTestingTreeNode.cpp
index b9a7455f3e..17f302aa5c 100644
--- a/gfx/layers/apz/src/HitTestingTreeNode.cpp
+++ b/gfx/layers/apz/src/HitTestingTreeNode.cpp
@@ -10,6 +10,7 @@
 #include "LayersLogging.h"                              // for Stringify
 #include "mozilla/gfx/Point.h"                          // for Point4D
 #include "mozilla/layers/APZThreadUtils.h"              // for AssertOnCompositorThread
+#include "mozilla/layers/APZUtils.h"                    // for CompleteAsyncTransform
 #include "mozilla/layers/AsyncCompositionManager.h"     // for ViewTransform::operator Matrix4x4()
 #include "nsPrintfCString.h"                            // for nsPrintfCString
 #include "UnitTransforms.h"                             // for ViewAs
@@ -209,7 +210,7 @@ HitTestingTreeNode::GetLayersId() const
 
 void
 HitTestingTreeNode::SetHitTestData(const EventRegions& aRegions,
-                                   const gfx::Matrix4x4& aTransform,
+                                   const CSSTransformMatrix& aTransform,
                                    const Maybe<ParentLayerIntRegion>& aClipRegion,
                                    const EventRegionsOverride& aOverride)
 {
@@ -230,12 +231,12 @@ Maybe<LayerPoint>
 HitTestingTreeNode::Untransform(const ParentLayerPoint& aPoint) const
 {
   // convert into Layer coordinate space
-  gfx::Matrix4x4 localTransform = mTransform;
-  if (mApzc) {
-    localTransform = localTransform * mApzc->GetCurrentAsyncTransformWithOverscroll();
-  }
-  return UntransformBy(
-      ViewAs<LayerToParentLayerMatrix4x4>(localTransform).Inverse(), aPoint);
+  LayerToParentLayerMatrix4x4 transform = mTransform *
+      CompleteAsyncTransform(
+        mApzc
+      ? mApzc->GetCurrentAsyncTransformWithOverscroll()
+      : AsyncTransformComponentMatrix());
+  return UntransformBy(transform.Inverse(), aPoint);
 }
 
 HitTestResult
diff --git a/gfx/layers/apz/src/HitTestingTreeNode.h b/gfx/layers/apz/src/HitTestingTreeNode.h
index 0bf8cf6970..98c6ec11d7 100644
--- a/gfx/layers/apz/src/HitTestingTreeNode.h
+++ b/gfx/layers/apz/src/HitTestingTreeNode.h
@@ -85,7 +85,7 @@ public:
   /* Hit test related methods */
 
   void SetHitTestData(const EventRegions& aRegions,
-                      const gfx::Matrix4x4& aTransform,
+                      const CSSTransformMatrix& aTransform,
                       const Maybe<ParentLayerIntRegion>& aClipRegion,
                       const EventRegionsOverride& aOverride);
   bool IsOutsideClip(const ParentLayerPoint& aPoint) const;
@@ -135,7 +135,7 @@ private:
 
   /* This is the transform from layer L. This does NOT include any async
    * transforms. */
-  gfx::Matrix4x4 mTransform;
+  CSSTransformMatrix mTransform;
 
   /* This is clip rect for L that we wish to use for hit-testing purposes. Note
    * that this may not be exactly the same as the clip rect on layer L because
diff --git a/gfx/layers/client/TextureClient.cpp b/gfx/layers/client/TextureClient.cpp
index a45be41cca..a2eeb3a80b 100644
--- a/gfx/layers/client/TextureClient.cpp
+++ b/gfx/layers/client/TextureClient.cpp
@@ -727,7 +727,6 @@ TextureClient::CreateForDrawing(CompositableForwarder* aAllocator,
   }
 
   if (!data && aFormat == SurfaceFormat::B8G8R8X8 &&
-      aAllocator->IsSameProcess() &&
       moz2DBackend == gfx::BackendType::CAIRO &&
       NS_IsMainThread()) {
     data = DIBTextureData::Create(aSize, aFormat, aAllocator);
diff --git a/gfx/layers/client/TiledContentClient.cpp b/gfx/layers/client/TiledContentClient.cpp
index 1d1e94e14c..85e43f8230 100644
--- a/gfx/layers/client/TiledContentClient.cpp
+++ b/gfx/layers/client/TiledContentClient.cpp
@@ -772,7 +772,7 @@ TileClient::GetBackBuffer(const nsIntRegion& aDirtyRegion,
 
       mBackBuffer.Set(this, mAllocator->GetTextureClient());
       if (!mBackBuffer) {
-        gfxCriticalError() << "[Tiling:Client] Failed to allocate a TextureClient";
+        gfxCriticalError() << "[Tiling:Client] Failed to allocate a TextureClient (B)";
         return nullptr;
       }
 
@@ -780,7 +780,7 @@ TileClient::GetBackBuffer(const nsIntRegion& aDirtyRegion,
         mBackBufferOnWhite = mAllocator->GetTextureClient();
         if (!mBackBufferOnWhite) {
           mBackBuffer.Set(this, nullptr);
-          gfxCriticalError() << "[Tiling:Client] Failed to allocate a TextureClient";
+          gfxCriticalError() << "[Tiling:Client] Failed to allocate a TextureClient (W)";
           return nullptr;
         }
       }
@@ -805,7 +805,7 @@ TileClient::GetBackBuffer(const nsIntRegion& aDirtyRegion,
 
   if (!mBackBuffer->IsLocked()) {
     if (!mBackBuffer->Lock(OpenMode::OPEN_READ_WRITE)) {
-      gfxCriticalError() << "[Tiling:Client] Failed to lock a tile";
+      gfxCriticalError() << "[Tiling:Client] Failed to lock a tile (B)";
       DiscardBackBuffer();
       DiscardFrontBuffer();
       return nullptr;
@@ -814,7 +814,7 @@ TileClient::GetBackBuffer(const nsIntRegion& aDirtyRegion,
 
   if (mBackBufferOnWhite && !mBackBufferOnWhite->IsLocked()) {
     if (!mBackBufferOnWhite->Lock(OpenMode::OPEN_READ_WRITE)) {
-      gfxCriticalError() << "[Tiling:Client] Failed to lock a tile";
+      gfxCriticalError() << "[Tiling:Client] Failed to lock a tile (W)";
       DiscardBackBuffer();
       DiscardFrontBuffer();
       return nullptr;
@@ -1406,7 +1406,7 @@ GetCompositorSideCompositionBounds(const LayerMetricsWrapper& aScrollAncestor,
                                    const LayerRect& aClip)
 {
   LayerToParentLayerMatrix4x4 transform = aTransformToCompBounds *
-      ViewAs<ParentLayerToParentLayerMatrix4x4>(aAPZTransform);
+      AsyncTransformComponentMatrix(aAPZTransform);
 
   return UntransformBy(transform.Inverse(),
     aScrollAncestor.Metrics().GetCompositionBounds(), aClip);
diff --git a/gfx/layers/composite/AsyncCompositionManager.cpp b/gfx/layers/composite/AsyncCompositionManager.cpp
index 476c68db18..3ddba54f9c 100644
--- a/gfx/layers/composite/AsyncCompositionManager.cpp
+++ b/gfx/layers/composite/AsyncCompositionManager.cpp
@@ -20,6 +20,7 @@
 #include "mozilla/gfx/Point.h"          // for RoundedToInt, PointTyped
 #include "mozilla/gfx/Rect.h"           // for RoundedToInt, RectTyped
 #include "mozilla/gfx/ScaleFactor.h"    // for ScaleFactor
+#include "mozilla/layers/APZUtils.h"    // for CompleteAsyncTransform
 #include "mozilla/layers/Compositor.h"  // for Compositor
 #include "mozilla/layers/CompositorParent.h" // for CompositorParent, etc
 #include "mozilla/layers/LayerMetricsWrapper.h" // for LayerMetricsWrapper
@@ -221,7 +222,7 @@ TransformClipRect(Layer* aLayer,
  * only be applied once.
  */
 static void
-SetShadowTransform(Layer* aLayer, Matrix4x4 aTransform)
+SetShadowTransform(Layer* aLayer, LayerToParentLayerMatrix4x4 aTransform)
 {
   if (ContainerLayer* c = aLayer->AsContainerLayer()) {
     aTransform.PreScale(1.0f / c->GetPreXScale(),
@@ -231,7 +232,7 @@ SetShadowTransform(Layer* aLayer, Matrix4x4 aTransform)
   aTransform.PostScale(1.0f / aLayer->GetPostXScale(),
                        1.0f / aLayer->GetPostYScale(),
                        1);
-  aLayer->AsLayerComposite()->SetShadowTransform(aTransform);
+  aLayer->AsLayerComposite()->SetShadowTransform(aTransform.ToUnknownMatrix());
 }
 
 static void
@@ -245,7 +246,7 @@ TranslateShadowLayer(Layer* aLayer,
   // Note that the shadow transform is reset on every frame of composition so
   // we don't have to worry about the adjustments compounding over successive
   // frames.
-  Matrix4x4 layerTransform = aLayer->GetLocalTransform();
+  LayerToParentLayerMatrix4x4 layerTransform = aLayer->GetLocalTransformTyped();
 
   // Apply the translation to the layer transform.
   layerTransform.PostTranslate(aTranslation.x, aTranslation.y, 0);
@@ -383,8 +384,8 @@ void
 AsyncCompositionManager::AlignFixedAndStickyLayers(Layer* aLayer,
                                                    Layer* aTransformedSubtreeRoot,
                                                    FrameMetrics::ViewID aTransformScrollId,
-                                                   const Matrix4x4& aPreviousTransformForRoot,
-                                                   const Matrix4x4& aCurrentTransformForRoot,
+                                                   const LayerToParentLayerMatrix4x4& aPreviousTransformForRoot,
+                                                   const LayerToParentLayerMatrix4x4& aCurrentTransformForRoot,
                                                    const ScreenMargin& aFixedLayerMargins,
                                                    bool aTransformAffectsLayerClip)
 {
@@ -428,8 +429,8 @@ AsyncCompositionManager::AlignFixedAndStickyLayers(Layer* aLayer,
 
   // Calculate the cumulative transforms between the subtree root with the
   // old transform and the current transform.
-  Matrix4x4 oldCumulativeTransform = ancestorTransform * aPreviousTransformForRoot;
-  Matrix4x4 newCumulativeTransform = ancestorTransform * aCurrentTransformForRoot;
+  Matrix4x4 oldCumulativeTransform = ancestorTransform * aPreviousTransformForRoot.ToUnknownMatrix();
+  Matrix4x4 newCumulativeTransform = ancestorTransform * aCurrentTransformForRoot.ToUnknownMatrix();
   if (newCumulativeTransform.IsSingular()) {
     return;
   }
@@ -698,10 +699,10 @@ AsyncCompositionManager::RecordShadowTransforms(Layer* aLayer)
   }
 }
 
-Matrix4x4
-AdjustForClip(const Matrix4x4& asyncTransform, Layer* aLayer)
+static AsyncTransformComponentMatrix
+AdjustForClip(const AsyncTransformComponentMatrix& asyncTransform, Layer* aLayer)
 {
-  Matrix4x4 result = asyncTransform;
+  AsyncTransformComponentMatrix result = asyncTransform;
 
   // Container layers start at the origin, but they are clipped to where they
   // actually have content on the screen. The tree transform is meant to apply
@@ -802,9 +803,10 @@ AsyncCompositionManager::ApplyAsyncContentTransformToTree(Layer *aLayer,
           clipDeferredFromChildren);
   }
 
-  Matrix4x4 oldTransform = aLayer->GetTransform();
+  LayerToParentLayerMatrix4x4 oldTransform = aLayer->GetTransformTyped() *
+      AsyncTransformMatrix();
 
-  Matrix4x4 combinedAsyncTransform;
+  AsyncTransformComponentMatrix combinedAsyncTransform;
   bool hasAsyncTransform = false;
   ScreenMargin fixedLayerMargins;
 
@@ -840,9 +842,10 @@ AsyncCompositionManager::ApplyAsyncContentTransformToTree(Layer *aLayer,
     ParentLayerPoint scrollOffset;
     controller->SampleContentTransformForFrame(&asyncTransformWithoutOverscroll,
                                                scrollOffset);
-    Matrix4x4 overscrollTransform = controller->GetOverscrollTransform();
-    Matrix4x4 asyncTransform =
-      Matrix4x4(asyncTransformWithoutOverscroll) * overscrollTransform;
+    AsyncTransformComponentMatrix overscrollTransform = controller->GetOverscrollTransform();
+    AsyncTransformComponentMatrix asyncTransform =
+        AsyncTransformComponentMatrix(asyncTransformWithoutOverscroll)
+      * overscrollTransform;
 
     if (!aLayer->IsScrollInfoLayer()) {
       controller->MarkAsyncTransformAppliedToContent();
@@ -898,8 +901,7 @@ AsyncCompositionManager::ApplyAsyncContentTransformToTree(Layer *aLayer,
     // frame and should not be transformed.
     if (asyncClip && !metrics.UsesContainerScrolling()) {
       MOZ_ASSERT(asyncTransform.Is2D());
-      asyncClip = Some(TransformBy(
-          ViewAs<ParentLayerToParentLayerMatrix4x4>(asyncTransform), *asyncClip));
+      asyncClip = Some(TransformBy(asyncTransform, *asyncClip));
     }
     aLayer->AsLayerComposite()->SetShadowClipRect(asyncClip);
 
@@ -912,8 +914,10 @@ AsyncCompositionManager::ApplyAsyncContentTransformToTree(Layer *aLayer,
     // effects apply to fixed and sticky layers. We do this by using
     // GetTransform() as the base transform rather than GetLocalTransform(),
     // which would include those factors.
-    Matrix4x4 transformWithoutOverscrollOrOmta = aLayer->GetTransform() *
-        AdjustForClip(asyncTransformWithoutOverscroll, aLayer);
+    LayerToParentLayerMatrix4x4 transformWithoutOverscrollOrOmta =
+        aLayer->GetTransformTyped()
+      * CompleteAsyncTransform(
+          AdjustForClip(asyncTransformWithoutOverscroll, aLayer));
 
     // Since fixed/sticky layers are relative to their nearest scrolling ancestor,
     // we use the ViewID from the bottommost scrollable metrics here.
@@ -947,7 +951,7 @@ AsyncCompositionManager::ApplyAsyncContentTransformToTree(Layer *aLayer,
     // frame, so these are the ones we need to shift by our async transform.
     for (Layer* ancestorMaskLayer : ancestorMaskLayers) {
       SetShadowTransform(ancestorMaskLayer,
-          ancestorMaskLayer->GetLocalTransform() * asyncTransform);
+          ancestorMaskLayer->GetLocalTransformTyped() * asyncTransform);
     }
 
     // Append the ancestor mask layer for this scroll frame to ancestorMaskLayers.
@@ -969,12 +973,13 @@ AsyncCompositionManager::ApplyAsyncContentTransformToTree(Layer *aLayer,
     // shadow transform; in that case we want to apply ours on top of that one
     // rather than clobber it.
     SetShadowTransform(aLayer,
-        aLayer->GetLocalTransform() * AdjustForClip(combinedAsyncTransform, aLayer));
+        aLayer->GetLocalTransformTyped()
+      * AdjustForClip(combinedAsyncTransform, aLayer));
 
     // Do the same for the layer's own mask layer, if it has one.
     if (Layer* maskLayer = aLayer->GetMaskLayer()) {
       SetShadowTransform(maskLayer,
-          maskLayer->GetLocalTransform() * combinedAsyncTransform);
+          maskLayer->GetLocalTransformTyped() * combinedAsyncTransform);
     }
 
     appliedTransform = true;
@@ -1019,13 +1024,13 @@ ApplyAsyncTransformToScrollbarForContent(Layer* aScrollbar,
   const FrameMetrics& metrics = aContent.Metrics();
   AsyncPanZoomController* apzc = aContent.GetApzc();
 
-  Matrix4x4 asyncTransform = apzc->GetCurrentAsyncTransform();
+  AsyncTransformComponentMatrix asyncTransform = apzc->GetCurrentAsyncTransform();
 
   // |asyncTransform| represents the amount by which we have scrolled and
   // zoomed since the last paint. Because the scrollbar was sized and positioned based
   // on the painted content, we need to adjust it based on asyncTransform so that
   // it reflects what the user is actually seeing now.
-  Matrix4x4 scrollbarTransform;
+  AsyncTransformComponentMatrix scrollbarTransform;
   if (aScrollbar->GetScrollbarDirection() == Layer::VERTICAL) {
     const ParentLayerCoord asyncScrollY = asyncTransform._42;
     const float asyncZoomY = asyncTransform._22;
@@ -1106,9 +1111,10 @@ ApplyAsyncTransformToScrollbarForContent(Layer* aScrollbar,
     scrollbarTransform.PostTranslate(xTranslation, 0, 0);
   }
 
-  Matrix4x4 transform = aScrollbar->GetLocalTransform() * scrollbarTransform;
+  LayerToParentLayerMatrix4x4 transform =
+      aScrollbar->GetLocalTransformTyped() * scrollbarTransform;
 
-  Matrix4x4 compensation;
+  AsyncTransformComponentMatrix compensation;
   // If the scrollbar layer is for the root then the content's resolution
   // applies to the scrollbar as well. Since we don't actually want the scroll
   // thumb's size to vary with the zoom (other than its length reflecting the
@@ -1116,9 +1122,10 @@ ApplyAsyncTransformToScrollbarForContent(Layer* aScrollbar,
   // above), we apply a transform to cancel out this resolution.
   if (metrics.IsRootContent()) {
     compensation =
-        Matrix4x4::Scaling(metrics.GetPresShellResolution(),
-                           metrics.GetPresShellResolution(),
-                           1.0f).Inverse();
+        AsyncTransformComponentMatrix::Scaling(
+            metrics.GetPresShellResolution(),
+            metrics.GetPresShellResolution(),
+            1.0f).Inverse();
   }
   // If the scrollbar layer is a child of the content it is a scrollbar for,
   // then we need to adjust for any async transform (including an overscroll
@@ -1132,13 +1139,15 @@ ApplyAsyncTransformToScrollbarForContent(Layer* aScrollbar,
   // the same coordinate space. This requires applying the content transform
   // and then unapplying it after unapplying the async transform.
   if (aScrollbarIsDescendant) {
-    Matrix4x4 asyncUntransform = (asyncTransform * apzc->GetOverscrollTransform()).Inverse();
+    Matrix4x4 asyncUntransform = (asyncTransform * apzc->GetOverscrollTransform()).Inverse().ToUnknownMatrix();
     Matrix4x4 contentTransform = aContent.GetTransform();
     Matrix4x4 contentUntransform = contentTransform.Inverse();
 
-    Matrix4x4 asyncCompensation = contentTransform
-                                * asyncUntransform
-                                * contentUntransform;
+    AsyncTransformComponentMatrix asyncCompensation =
+        ViewAs<AsyncTransformComponentMatrix>(
+            contentTransform
+          * asyncUntransform
+          * contentUntransform);
 
     compensation = compensation * asyncCompensation;
 
@@ -1147,7 +1156,7 @@ ApplyAsyncTransformToScrollbarForContent(Layer* aScrollbar,
     // including the layer with the async transform. Otherwise the scrollbar
     // shifts but gets clipped and so appears to flicker.
     for (Layer* ancestor = aScrollbar; ancestor != aContent.GetLayer(); ancestor = ancestor->GetParent()) {
-      TransformClipRect(ancestor, ViewAs<ParentLayerToParentLayerMatrix4x4>(asyncCompensation));
+      TransformClipRect(ancestor, asyncCompensation);
     }
   }
   transform = transform * compensation;
@@ -1236,7 +1245,8 @@ AsyncCompositionManager::TransformScrollableLayer(Layer* aLayer)
 
   // We must apply the resolution scale before a pan/zoom transform, so we call
   // GetTransform here.
-  Matrix4x4 oldTransform = aLayer->GetTransform();
+  LayerToParentLayerMatrix4x4 oldTransform = aLayer->GetTransformTyped() *
+      AsyncTransformMatrix();
 
   CSSToLayerScale geckoZoom = metrics.LayersPixelsPerCSSPixel().ToScaleFactor();
 
@@ -1295,13 +1305,13 @@ AsyncCompositionManager::TransformScrollableLayer(Layer* aLayer)
 
   LayerToParentLayerScale asyncZoom = userZoom / metrics.LayersPixelsPerCSSPixel().ToScaleFactor();
   ParentLayerPoint translation = userRect.TopLeft() - geckoScroll;
-  Matrix4x4 treeTransform = AsyncTransform(asyncZoom, -translation);
+  AsyncTransformComponentMatrix treeTransform = AsyncTransform(asyncZoom, -translation);
 
   // Apply the tree transform on top of GetLocalTransform() here (rather than
   // GetTransform()) in case the OMTA code in SampleAnimations already set a
   // shadow transform; in that case we want to apply ours on top of that one
   // rather than clobber it.
-  SetShadowTransform(aLayer, aLayer->GetLocalTransform() * treeTransform);
+  SetShadowTransform(aLayer, aLayer->GetLocalTransformTyped() * treeTransform);
 
   // Make sure that overscroll and under-zoom are represented in the old
   // transform so that fixed position content moves and scales accordingly.
@@ -1338,8 +1348,8 @@ AsyncCompositionManager::TransformScrollableLayer(Layer* aLayer)
   // Make sure fixed position layers don't move away from their anchor points
   // when we're asynchronously panning or zooming
   AlignFixedAndStickyLayers(aLayer, aLayer, metrics.GetScrollId(), oldTransform,
-                            aLayer->GetLocalTransform(), fixedLayerMargins,
-                            false);
+                            aLayer->GetLocalTransformTyped(),
+                            fixedLayerMargins, false);
 
   ExpandRootClipRect(aLayer, fixedLayerMargins);
 }
diff --git a/gfx/layers/composite/AsyncCompositionManager.h b/gfx/layers/composite/AsyncCompositionManager.h
index e21e4da62f..76cca8fdc0 100644
--- a/gfx/layers/composite/AsyncCompositionManager.h
+++ b/gfx/layers/composite/AsyncCompositionManager.h
@@ -36,17 +36,10 @@ struct AsyncTransform {
     , mTranslation(aTranslation)
   {}
 
-  operator gfx::Matrix4x4() const
+  operator AsyncTransformComponentMatrix() const
   {
-    return
-      gfx::Matrix4x4::Scaling(mScale.scale, mScale.scale, 1)
-                      .PostTranslate(mTranslation.x, mTranslation.y, 0);
-  }
-
-  // For convenience, to avoid writing the cumbersome
-  // "gfx::Matrix4x4(a) * gfx::Matrix4x4(b)".
-  friend gfx::Matrix4x4 operator*(const AsyncTransform& a, const AsyncTransform& b) {
-    return gfx::Matrix4x4(a) * gfx::Matrix4x4(b);
+    return AsyncTransformComponentMatrix::Scaling(mScale.scale, mScale.scale, 1)
+        .PostTranslate(mTranslation.x, mTranslation.y, 0);
   }
 
   bool operator==(const AsyncTransform& rhs) const {
@@ -184,8 +177,8 @@ private:
    */
   void AlignFixedAndStickyLayers(Layer* aLayer, Layer* aTransformedSubtreeRoot,
                                  FrameMetrics::ViewID aTransformScrollId,
-                                 const gfx::Matrix4x4& aPreviousTransformForRoot,
-                                 const gfx::Matrix4x4& aCurrentTransformForRoot,
+                                 const LayerToParentLayerMatrix4x4& aPreviousTransformForRoot,
+                                 const LayerToParentLayerMatrix4x4& aCurrentTransformForRoot,
                                  const ScreenMargin& aFixedLayerMargins,
                                  bool aTransformAffectsLayerClip);
 
diff --git a/gfx/layers/composite/ContainerLayerComposite.cpp b/gfx/layers/composite/ContainerLayerComposite.cpp
index fae60c27e4..db65a61f8e 100755
--- a/gfx/layers/composite/ContainerLayerComposite.cpp
+++ b/gfx/layers/composite/ContainerLayerComposite.cpp
@@ -608,7 +608,7 @@ RenderLayers(ContainerT* aContainer,
                                                    gfx::Rect(aClipRect.ToUnknownRect()),
                                                    asyncTransform * aContainer->GetEffectiveTransform());
         if (AsyncPanZoomController* apzc = layer->GetAsyncPanZoomController(i - 1)) {
-          asyncTransform = apzc->GetCurrentAsyncTransformWithOverscroll()
+          asyncTransform = apzc->GetCurrentAsyncTransformWithOverscroll().ToUnknownMatrix()
                          * asyncTransform;
         }
       }
@@ -758,7 +758,7 @@ ContainerRender(ContainerT* aContainer,
     for (LayerMetricsWrapper i(aContainer); i; i = i.GetFirstChild()) {
       if (AsyncPanZoomController* apzc = i.GetApzc()) {
         if (!apzc->GetAsyncTransformAppliedToContent()
-            && !Matrix4x4(apzc->GetCurrentAsyncTransform()).IsIdentity()) {
+            && !AsyncTransformComponentMatrix(apzc->GetCurrentAsyncTransform()).IsIdentity()) {
           aManager->UnusedApzTransformWarning();
           break;
         }
diff --git a/gfx/layers/d3d11/TextureD3D11.cpp b/gfx/layers/d3d11/TextureD3D11.cpp
index 2bbe1410a1..cb3c3b28de 100644
--- a/gfx/layers/d3d11/TextureD3D11.cpp
+++ b/gfx/layers/d3d11/TextureD3D11.cpp
@@ -731,13 +731,13 @@ D3D11TextureData::UpdateFromSurface(gfx::SourceSurface* aSurface)
   RefPtr<DataSourceSurface> srcSurf = aSurface->GetDataSurface();
 
   if (!srcSurf) {
-    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface.";
+    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface (D3D11).";
     return false;
   }
 
   DataSourceSurface::MappedSurface sourceMap;
   if (!srcSurf->Map(DataSourceSurface::READ, &sourceMap)) {
-    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface.";
+    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface (D3D11).";
     return false;
   }
 
@@ -764,13 +764,13 @@ D3D10TextureData::UpdateFromSurface(gfx::SourceSurface* aSurface)
   RefPtr<DataSourceSurface> srcSurf = aSurface->GetDataSurface();
 
   if (!srcSurf) {
-    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface.";
+    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface (D3D10).";
     return false;
   }
 
   DataSourceSurface::MappedSurface sourceMap;
   if (!srcSurf->Map(DataSourceSurface::READ, &sourceMap)) {
-    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface.";
+    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface (D3D10).";
     return false;
   }
 
@@ -1262,7 +1262,7 @@ SyncObjectD3D11::FinalizeFrame()
     if (FAILED(hr) || !mutex) {
       // Leave both the critical error and MOZ_CRASH for now; the critical error lets
       // us "save" the hr value.  We will probably eventuall replace this with gfxDevCrash.
-      gfxCriticalError() << "Failed to get KeyedMutex: " << hexa(hr);
+      gfxCriticalError() << "Failed to get KeyedMutex (1): " << hexa(hr);
       MOZ_CRASH("GFX: Cannot get D3D10 KeyedMutex");
     }
   }
@@ -1289,7 +1289,7 @@ SyncObjectD3D11::FinalizeFrame()
     if (FAILED(hr) || !mutex) {
       // Leave both the critical error and MOZ_CRASH for now; the critical error lets
       // us "save" the hr value.  We will probably eventuall replace this with gfxDevCrash.
-      gfxCriticalError() << "Failed to get KeyedMutex: " << hexa(hr);
+      gfxCriticalError() << "Failed to get KeyedMutex (2): " << hexa(hr);
       MOZ_CRASH("GFX: Cannot get D3D11 KeyedMutex");
     }
   }
diff --git a/gfx/layers/d3d9/DeviceManagerD3D9.cpp b/gfx/layers/d3d9/DeviceManagerD3D9.cpp
index 99ecd4620c..e0dd13db29 100644
--- a/gfx/layers/d3d9/DeviceManagerD3D9.cpp
+++ b/gfx/layers/d3d9/DeviceManagerD3D9.cpp
@@ -359,13 +359,13 @@ DeviceManagerD3D9::Init()
     mNv3DVUtils->SetDeviceInfo(devUnknown); 
   } 
 
-  auto failCreateShaderMsg = "[D3D9] failed to create a critical resource (shader) code: ";
+  auto failCreateShaderMsg = "[D3D9] failed to create a critical resource (shader) code";
 
   hr = mDevice->CreateVertexShader((DWORD*)LayerQuadVS,
                                    getter_AddRefs(mLayerVS));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "LayerQuadVS: " << gfx::hexa(hr);
     return false;
   }
 
@@ -373,7 +373,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mRGBPS));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "RGBShaderPS: " << gfx::hexa(hr);
     return false;
   }
 
@@ -381,7 +381,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mRGBAPS));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "RGBAShaderPS: " << gfx::hexa(hr);
     return false;
   }
 
@@ -389,7 +389,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mComponentPass1PS));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "ComponentPass1ShaderPS: " << gfx::hexa(hr);
     return false;
   }
 
@@ -397,7 +397,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mComponentPass2PS));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "ComponentPass2ShaderPS: " << gfx::hexa(hr);
     return false;
   }
 
@@ -405,7 +405,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mYCbCrPS));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "YCbCrShaderPS: " << gfx::hexa(hr);
     return false;
   }
 
@@ -413,7 +413,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mSolidColorPS));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg;
+    gfxCriticalError() << failCreateShaderMsg << "SolidColorShaderPS" << gfx::hexa(hr);
     return false;
   }
 
@@ -421,14 +421,14 @@ DeviceManagerD3D9::Init()
                                    getter_AddRefs(mLayerVSMask));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "LayerQuadVSMask: " << gfx::hexa(hr);
     return false;
   }
   hr = mDevice->CreateVertexShader((DWORD*)LayerQuadVSMask3D,
                                    getter_AddRefs(mLayerVSMask3D));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "LayerQuadVSMask3D: " << gfx::hexa(hr);
     return false;
   }
 
@@ -436,7 +436,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mRGBPSMask));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "RGBShaderPSMask " << gfx::hexa(hr);
     return false;
   }
 
@@ -444,7 +444,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mRGBAPSMask));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "RGBAShaderPSMask: " << gfx::hexa(hr);
     return false;
   }
 
@@ -452,7 +452,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mRGBAPSMask3D));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "RGBAShaderPSMask3D: " << gfx::hexa(hr);
     return false;
   }
 
@@ -460,7 +460,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mComponentPass1PSMask));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "ComponentPass1ShaderPSMask: " << gfx::hexa(hr);
     return false;
   }
 
@@ -468,7 +468,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mComponentPass2PSMask));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg;
+    gfxCriticalError() << failCreateShaderMsg << "ComponentPass2ShaderPSMask: ";
     return false;
   }
 
@@ -476,7 +476,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mYCbCrPSMask));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "YCbCrShaderPSMask: " << gfx::hexa(hr);
     return false;
   }
 
@@ -484,7 +484,7 @@ DeviceManagerD3D9::Init()
                                   getter_AddRefs(mSolidColorPSMask));
 
   if (FAILED(hr)) {
-    gfxCriticalError() << failCreateShaderMsg << gfx::hexa(hr);
+    gfxCriticalError() << failCreateShaderMsg << "SolidColorShaderPSMask: " << gfx::hexa(hr);
     return false;
   }
 
diff --git a/gfx/layers/d3d9/TextureD3D9.cpp b/gfx/layers/d3d9/TextureD3D9.cpp
index 5c8fff61c1..26c26b69d0 100644
--- a/gfx/layers/d3d9/TextureD3D9.cpp
+++ b/gfx/layers/d3d9/TextureD3D9.cpp
@@ -553,7 +553,7 @@ D3D9TextureData::BorrowDrawTarget()
     D3DLOCKED_RECT rect;
     HRESULT hr = mD3D9Surface->LockRect(&rect, nullptr, 0);
     if (FAILED(hr) || !rect.pBits) {
-      gfxCriticalError() << "Failed to lock rect borrowing the target in D3D9 " << hexa(hr);
+      gfxCriticalError() << "Failed to lock rect borrowing the target in D3D9 (BDT) " << hexa(hr);
       return nullptr;
     }
     dt = gfxPlatform::GetPlatform()->CreateDrawTargetForData((uint8_t*)rect.pBits, mSize,
@@ -588,21 +588,21 @@ D3D9TextureData::UpdateFromSurface(gfx::SourceSurface* aSurface)
   D3DLOCKED_RECT rect;
   HRESULT hr = mD3D9Surface->LockRect(&rect, nullptr, 0);
   if (FAILED(hr) || !rect.pBits) {
-    gfxCriticalError() << "Failed to lock rect borrowing the target in D3D9 " << hexa(hr);
+    gfxCriticalError() << "Failed to lock rect borrowing the target in D3D9 (UFS) " << hexa(hr);
     return false;
   }
 
   RefPtr<DataSourceSurface> srcSurf = aSurface->GetDataSurface();
 
   if (!srcSurf) {
-    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface.";
+    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface (D3D9).";
     mD3D9Surface->UnlockRect();
     return false;
   }
 
   DataSourceSurface::MappedSurface sourceMap;
   if (!srcSurf->Map(DataSourceSurface::READ, &sourceMap)) {
-    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface.";
+    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface (D3D9).";
     return false;
   }
 
diff --git a/gfx/layers/opengl/GrallocTextureClient.cpp b/gfx/layers/opengl/GrallocTextureClient.cpp
index 7feded01cb..35cbb09d4c 100644
--- a/gfx/layers/opengl/GrallocTextureClient.cpp
+++ b/gfx/layers/opengl/GrallocTextureClient.cpp
@@ -250,7 +250,7 @@ GrallocTextureData::UpdateFromSurface(gfx::SourceSurface* aSurface)
   RefPtr<DataSourceSurface> srcSurf = aSurface->GetDataSurface();
 
   if (!srcSurf) {
-    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface.";
+    gfxCriticalError() << "Failed to GetDataSurface in UpdateFromSurface (GTC).";
     return false;
   }
 
@@ -266,7 +266,7 @@ GrallocTextureData::UpdateFromSurface(gfx::SourceSurface* aSurface)
   DataSourceSurface::MappedSurface sourceMap;
 
   if (!srcSurf->Map(DataSourceSurface::READ, &sourceMap)) {
-    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface.";
+    gfxCriticalError() << "Failed to map source surface for UpdateFromSurface (GTC).";
     return false;
   }
 
diff --git a/gfx/thebes/gfxWindowsPlatform.cpp b/gfx/thebes/gfxWindowsPlatform.cpp
index d78e550f0a..1b7be02ecb 100644
--- a/gfx/thebes/gfxWindowsPlatform.cpp
+++ b/gfx/thebes/gfxWindowsPlatform.cpp
@@ -1777,7 +1777,7 @@ CheckForAdapterMismatch(ID3D11Device *device)
   nsresult ec;
   int32_t vendor = vendorID.ToInteger(&ec, 16);
   if (vendor != desc.VendorId) {
-      gfxCriticalNote << "VendorIDMismatch " << hexa(vendor) << " " << hexa(desc.VendorId);
+      gfxCriticalNote << "VendorIDMismatch V " << hexa(vendor) << " " << hexa(desc.VendorId);
   }
 }
 
@@ -2265,7 +2265,7 @@ gfxWindowsPlatform::ContentAdapterIsParentAdapter(ID3D11Device* device)
       desc.AdapterLuid.HighPart != parent.AdapterLuid.HighPart ||
       desc.AdapterLuid.LowPart != parent.AdapterLuid.LowPart)
   {
-    gfxCriticalNote << "VendorIDMismatch " << hexa(parent.VendorId) << " " << hexa(desc.VendorId);
+    gfxCriticalNote << "VendorIDMismatch P " << hexa(parent.VendorId) << " " << hexa(desc.VendorId);
     return false;
   }
 
diff --git a/layout/base/ActiveLayerTracker.cpp b/layout/base/ActiveLayerTracker.cpp
index 13026731fe..5f32dcdbe6 100644
--- a/layout/base/ActiveLayerTracker.cpp
+++ b/layout/base/ActiveLayerTracker.cpp
@@ -146,7 +146,7 @@ LayerActivity::~LayerActivity()
 }
 
 // Frames with this property have NS_FRAME_HAS_LAYER_ACTIVITY_PROPERTY set
-NS_DECLARE_FRAME_PROPERTY(LayerActivityProperty, DeleteValue<LayerActivity>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(LayerActivityProperty, LayerActivity)
 
 void
 LayerActivityTracker::NotifyExpired(LayerActivity* aObject)
@@ -188,15 +188,14 @@ GetLayerActivity(nsIFrame* aFrame)
     return nullptr;
   }
   FrameProperties properties = aFrame->Properties();
-  return static_cast<LayerActivity*>(properties.Get(LayerActivityProperty()));
+  return properties.Get(LayerActivityProperty());
 }
 
 static LayerActivity*
 GetLayerActivityForUpdate(nsIFrame* aFrame)
 {
   FrameProperties properties = aFrame->Properties();
-  LayerActivity* layerActivity =
-    static_cast<LayerActivity*>(properties.Get(LayerActivityProperty()));
+  LayerActivity* layerActivity = properties.Get(LayerActivityProperty());
   if (layerActivity) {
     gLayerActivityTracker->MarkUsed(layerActivity);
   } else {
@@ -224,8 +223,7 @@ ActiveLayerTracker::TransferActivityToContent(nsIFrame* aFrame, nsIContent* aCon
     return;
   }
   FrameProperties properties = aFrame->Properties();
-  LayerActivity* layerActivity =
-    static_cast<LayerActivity*>(properties.Remove(LayerActivityProperty()));
+  LayerActivity* layerActivity = properties.Remove(LayerActivityProperty());
   aFrame->RemoveStateBits(NS_FRAME_HAS_LAYER_ACTIVITY_PROPERTY);
   if (!layerActivity) {
     return;
diff --git a/layout/base/FrameLayerBuilder.cpp b/layout/base/FrameLayerBuilder.cpp
index 2f780a4362..f84aa561ff 100644
--- a/layout/base/FrameLayerBuilder.cpp
+++ b/layout/base/FrameLayerBuilder.cpp
@@ -1710,23 +1710,21 @@ GetTranslationForPaintedLayer(PaintedLayer* aLayer)
 
 /* static */ void
 FrameLayerBuilder::RemoveFrameFromLayerManager(const nsIFrame* aFrame,
-                                               void* aPropertyValue)
+                                               nsTArray<DisplayItemData*>* aArray)
 {
   MOZ_RELEASE_ASSERT(!sDestroyedFrame);
   sDestroyedFrame = aFrame;
-  nsTArray<DisplayItemData*> *array =
-    reinterpret_cast<nsTArray<DisplayItemData*>*>(aPropertyValue);
 
   // Hold a reference to all the items so that they don't get
   // deleted from under us.
   nsTArray<RefPtr<DisplayItemData> > arrayCopy;
-  for (uint32_t i = 0; i < array->Length(); ++i) {
-    arrayCopy.AppendElement(array->ElementAt(i));
+  for (DisplayItemData* data : *aArray) {
+    arrayCopy.AppendElement(data);
   }
 
 #ifdef DEBUG_DISPLAY_ITEM_DATA
-  if (array->Length()) {
-    LayerManagerData *rootData = array->ElementAt(0)->mParent;
+  if (aArray->Length()) {
+    LayerManagerData *rootData = aArray->ElementAt(0)->mParent;
     while (rootData->mParent) {
       rootData = rootData->mParent;
     }
@@ -1735,9 +1733,7 @@ FrameLayerBuilder::RemoveFrameFromLayerManager(const nsIFrame* aFrame,
   }
 #endif
 
-  for (uint32_t i = 0; i < array->Length(); ++i) {
-    DisplayItemData* data = array->ElementAt(i);
-
+  for (DisplayItemData* data : *aArray) {
     PaintedLayer* t = data->mLayer->AsPaintedLayer();
     if (t) {
       PaintedDisplayItemLayerUserData* paintedData =
@@ -1755,7 +1751,7 @@ FrameLayerBuilder::RemoveFrameFromLayerManager(const nsIFrame* aFrame,
   }
 
   arrayCopy.Clear();
-  delete array;
+  delete aArray;
   sDestroyedFrame = nullptr;
 }
 
diff --git a/layout/base/FrameLayerBuilder.h b/layout/base/FrameLayerBuilder.h
index 186d39a445..5f018d0fda 100644
--- a/layout/base/FrameLayerBuilder.h
+++ b/layout/base/FrameLayerBuilder.h
@@ -410,6 +410,7 @@ public:
   void StoreOptimizedLayerForFrame(nsDisplayItem* aItem, Layer* aLayer);
   
   NS_DECLARE_FRAME_PROPERTY_WITH_FRAME_IN_DTOR(LayerManagerDataProperty,
+                                               nsTArray<DisplayItemData*>,
                                                RemoveFrameFromLayerManager)
 
   /**
@@ -514,7 +515,8 @@ protected:
 
   friend class LayerManagerData;
 
-  static void RemoveFrameFromLayerManager(const nsIFrame* aFrame, void* aPropertyValue);
+  static void RemoveFrameFromLayerManager(const nsIFrame* aFrame,
+                                          nsTArray<DisplayItemData*>* aArray);
 
   /**
    * Given a frame and a display item key that uniquely identifies a
diff --git a/layout/base/FramePropertyTable.cpp b/layout/base/FramePropertyTable.cpp
index 1d180f770f..12a1dcc3de 100644
--- a/layout/base/FramePropertyTable.cpp
+++ b/layout/base/FramePropertyTable.cpp
@@ -10,9 +10,8 @@
 namespace mozilla {
 
 void
-FramePropertyTable::Set(const nsIFrame* aFrame,
-                        const FramePropertyDescriptor* aProperty,
-                        void* aValue)
+FramePropertyTable::SetInternal(
+  const nsIFrame* aFrame, UntypedDescriptor aProperty, void* aValue)
 {
   NS_ASSERTION(aFrame, "Null frame?");
   NS_ASSERTION(aProperty, "Null property?");
@@ -60,9 +59,8 @@ FramePropertyTable::Set(const nsIFrame* aFrame,
 }
 
 void*
-FramePropertyTable::Get(const nsIFrame* aFrame,
-                        const FramePropertyDescriptor* aProperty,
-                        bool* aFoundResult)
+FramePropertyTable::GetInternal(
+  const nsIFrame* aFrame, UntypedDescriptor aProperty, bool* aFoundResult)
 {
   NS_ASSERTION(aFrame, "Null frame?");
   NS_ASSERTION(aProperty, "Null property?");
@@ -104,9 +102,8 @@ FramePropertyTable::Get(const nsIFrame* aFrame,
 }
 
 void*
-FramePropertyTable::Remove(const nsIFrame* aFrame,
-                           const FramePropertyDescriptor* aProperty,
-                           bool* aFoundResult)
+FramePropertyTable::RemoveInternal(
+  const nsIFrame* aFrame, UntypedDescriptor aProperty, bool* aFoundResult)
 {
   NS_ASSERTION(aFrame, "Null frame?");
   NS_ASSERTION(aProperty, "Null property?");
@@ -166,14 +163,14 @@ FramePropertyTable::Remove(const nsIFrame* aFrame,
 }
 
 void
-FramePropertyTable::Delete(const nsIFrame* aFrame,
-                           const FramePropertyDescriptor* aProperty)
+FramePropertyTable::DeleteInternal(
+  const nsIFrame* aFrame, UntypedDescriptor aProperty)
 {
   NS_ASSERTION(aFrame, "Null frame?");
   NS_ASSERTION(aProperty, "Null property?");
 
   bool found;
-  void* v = Remove(aFrame, aProperty, &found);
+  void* v = RemoveInternal(aFrame, aProperty, &found);
   if (found) {
     PropertyValue pv(aProperty, v);
     pv.DestroyValueFor(aFrame);
diff --git a/layout/base/FramePropertyTable.h b/layout/base/FramePropertyTable.h
index bb0158b1ad..9688a8f159 100644
--- a/layout/base/FramePropertyTable.h
+++ b/layout/base/FramePropertyTable.h
@@ -6,6 +6,7 @@
 #ifndef FRAMEPROPERTYTABLE_H_
 #define FRAMEPROPERTYTABLE_H_
 
+#include "mozilla/TypeTraits.h"
 #include "mozilla/MemoryReporting.h"
 #include "nsTArray.h"
 #include "nsTHashtable.h"
@@ -15,28 +16,13 @@ class nsIFrame;
 
 namespace mozilla {
 
-struct FramePropertyDescriptor;
-
-typedef void (*FramePropertyDestructor)(void* aPropertyValue);
-typedef void (*FramePropertyDestructorWithFrame)(const nsIFrame* aFrame,
-                                                 void* aPropertyValue);
-
-/**
- * A pointer to a FramePropertyDescriptor serves as a unique property ID.
- * The FramePropertyDescriptor stores metadata about the property.
- * Currently the only metadata is a destructor function. The destructor
- * function is called on property values when they are overwritten or
- * deleted.
- * 
- * To use this class, declare a global (i.e., file, class or function-scope
- * static member) FramePropertyDescriptor and pass its address as
- * aProperty in the FramePropertyTable methods.
- */
-struct FramePropertyDescriptor {
+struct FramePropertyDescriptorUntyped
+{
   /**
    * mDestructor will be called if it's non-null.
    */
-  FramePropertyDestructor          mDestructor;
+  typedef void UntypedDestructor(void* aPropertyValue);
+  UntypedDestructor* mDestructor;
   /**
    * mDestructorWithFrame will be called if it's non-null and mDestructor
    * is null. WARNING: The frame passed to mDestructorWithFrame may
@@ -45,13 +31,104 @@ struct FramePropertyDescriptor {
    * other frame pointers. No frame will have been allocated with
    * the same address yet.
    */
-  FramePropertyDestructorWithFrame mDestructorWithFrame;
+  typedef void UntypedDestructorWithFrame(const nsIFrame* aFrame,
+                                          void* aPropertyValue);
+  UntypedDestructorWithFrame* mDestructorWithFrame;
   /**
    * mDestructor and mDestructorWithFrame may both be null, in which case
    * no value destruction is a no-op.
    */
+
+protected:
+  /**
+   * At most one destructor should be passed in. In general, you should
+   * just use the static function FramePropertyDescriptor::New* below
+   * instead of using this constructor directly.
+   */
+  MOZ_CONSTEXPR FramePropertyDescriptorUntyped(
+    UntypedDestructor* aDtor, UntypedDestructorWithFrame* aDtorWithFrame)
+    : mDestructor(aDtor)
+    , mDestructorWithFrame(aDtorWithFrame)
+  {}
 };
 
+/**
+ * A pointer to a FramePropertyDescriptor serves as a unique property ID.
+ * The FramePropertyDescriptor stores metadata about the property.
+ * Currently the only metadata is a destructor function. The destructor
+ * function is called on property values when they are overwritten or
+ * deleted.
+ *
+ * To use this class, declare a global (i.e., file, class or function-scope
+ * static member) FramePropertyDescriptor and pass its address as
+ * aProperty in the FramePropertyTable methods.
+ */
+template<typename T>
+struct FramePropertyDescriptor : public FramePropertyDescriptorUntyped
+{
+  typedef void Destructor(T* aPropertyValue);
+  typedef void DestructorWithFrame(const nsIFrame* aaFrame,
+                                   T* aPropertyValue);
+
+  template<Destructor Dtor>
+  static MOZ_CONSTEXPR const FramePropertyDescriptor<T> NewWithDestructor()
+  {
+    return { Destruct<Dtor>, nullptr };
+  }
+
+  template<DestructorWithFrame Dtor>
+  static MOZ_CONSTEXPR
+  const FramePropertyDescriptor<T> NewWithDestructorWithFrame()
+  {
+    return { nullptr, DestructWithFrame<Dtor> };
+  }
+
+  static MOZ_CONSTEXPR const FramePropertyDescriptor<T> NewWithoutDestructor()
+  {
+    return { nullptr, nullptr };
+  }
+
+private:
+  MOZ_CONSTEXPR FramePropertyDescriptor(
+    UntypedDestructor* aDtor, UntypedDestructorWithFrame* aDtorWithFrame)
+    : FramePropertyDescriptorUntyped(aDtor, aDtorWithFrame)
+  {}
+
+  template<Destructor Dtor>
+  static void Destruct(void* aPropertyValue)
+  {
+    Dtor(static_cast<T*>(aPropertyValue));
+  }
+
+  template<DestructorWithFrame Dtor>
+  static void DestructWithFrame(const nsIFrame* aFrame, void* aPropertyValue)
+  {
+    Dtor(aFrame, static_cast<T*>(aPropertyValue));
+  }
+};
+
+// SmallValueHolder<T> is a placeholder intended to be used as template
+// argument of FramePropertyDescriptor for types which can fit into the
+// size of a pointer directly. This class should never be defined, so
+// that we won't use it for unexpected purpose by mistake.
+template<typename T>
+class SmallValueHolder;
+
+namespace detail {
+
+template<typename T>
+struct FramePropertyTypeHelper
+{
+  typedef T* Type;
+};
+template<typename T>
+struct FramePropertyTypeHelper<SmallValueHolder<T>>
+{
+  typedef T Type;
+};
+
+}
+
 /**
  * The FramePropertyTable is optimized for storing 0 or 1 properties on
  * a given frame. Storing very large numbers of properties on a single
@@ -65,6 +142,13 @@ struct FramePropertyDescriptor {
  */
 class FramePropertyTable {
 public:
+  template<typename T>
+  using Descriptor = const FramePropertyDescriptor<T>*;
+  using UntypedDescriptor = const FramePropertyDescriptorUntyped*;
+
+  template<typename T>
+  using PropertyType = typename detail::FramePropertyTypeHelper<T>::Type;
+
   FramePropertyTable() : mLastFrame(nullptr), mLastEntry(nullptr)
   {
   }
@@ -79,40 +163,64 @@ public:
    * the properties of that frame. Any existing value for the property
    * is destroyed.
    */
-  void Set(const nsIFrame* aFrame, const FramePropertyDescriptor* aProperty,
-           void* aValue);
+  template<typename T>
+  void Set(const nsIFrame* aFrame, Descriptor<T> aProperty,
+           PropertyType<T> aValue)
+  {
+    ReinterpretHelper<T> helper{};
+    helper.value = aValue;
+    SetInternal(aFrame, aProperty, helper.ptr);
+  }
   /**
    * Get a property value for a frame. This requires one hashtable
    * lookup (using the frame as the key) and a linear search through
    * the properties of that frame. If the frame has no such property,
-   * returns null.
+   * returns zero-filled result, which means null for pointers and
+   * zero for integers and floating point types.
    * @param aFoundResult if non-null, receives a value 'true' iff
    * the frame has a value for the property. This lets callers
    * disambiguate a null result, which can mean 'no such property' or
    * 'property value is null'.
    */
-  void* Get(const nsIFrame* aFrame, const FramePropertyDescriptor* aProperty,
-            bool* aFoundResult = nullptr);
+  template<typename T>
+  PropertyType<T> Get(const nsIFrame* aFrame, Descriptor<T> aProperty,
+                      bool* aFoundResult = nullptr)
+  {
+    ReinterpretHelper<T> helper;
+    helper.ptr = GetInternal(aFrame, aProperty, aFoundResult);
+    return helper.value;
+  }
   /**
    * Remove a property value for a frame. This requires one hashtable
    * lookup (using the frame as the key) and a linear search through
    * the properties of that frame. The old property value is returned
    * (and not destroyed). If the frame has no such property,
-   * returns null.
+   * returns zero-filled result, which means null for pointers and
+   * zero for integers and floating point types.
    * @param aFoundResult if non-null, receives a value 'true' iff
    * the frame had a value for the property. This lets callers
    * disambiguate a null result, which can mean 'no such property' or
    * 'property value is null'.
    */
-  void* Remove(const nsIFrame* aFrame, const FramePropertyDescriptor* aProperty,
-               bool* aFoundResult = nullptr);
+  template<typename T>
+  PropertyType<T> Remove(const nsIFrame* aFrame, Descriptor<T> aProperty,
+                         bool* aFoundResult = nullptr)
+  {
+    ReinterpretHelper<T> helper;
+    helper.ptr = RemoveInternal(aFrame, aProperty, aFoundResult);
+    return helper.value;
+  }
   /**
    * Remove and destroy a property value for a frame. This requires one
    * hashtable lookup (using the frame as the key) and a linear search
    * through the properties of that frame. If the frame has no such
    * property, nothing happens.
    */
-  void Delete(const nsIFrame* aFrame, const FramePropertyDescriptor* aProperty);
+  template<typename T>
+  void Delete(const nsIFrame* aFrame, Descriptor<T> aProperty)
+  {
+    DeleteInternal(aFrame, aProperty);
+  }
   /**
    * Remove and destroy all property values for a frame. This requires one
    * hashtable lookup (using the frame as the key).
@@ -126,23 +234,47 @@ public:
   /**
    * Check if a property exists (added for TenFourFox issue 493).
    */
-  bool Has(const nsIFrame* aFrame, const FramePropertyDescriptor* aProperty)
+  template<typename T>
+  bool Has(const nsIFrame* aFrame, Descriptor<T> aProperty)
   {
     bool foundResult = false;
-    (void)Get(aFrame, aProperty, &foundResult);
+    mozilla::Unused << GetInternal(aFrame, aProperty, &foundResult);
     return foundResult;
   }
 
   size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
 
 protected:
+  void SetInternal(const nsIFrame* aFrame, UntypedDescriptor aProperty,
+                   void* aValue);
+
+  void* GetInternal(const nsIFrame* aFrame, UntypedDescriptor aProperty,
+                    bool* aFoundResult);
+
+  void* RemoveInternal(const nsIFrame* aFrame, UntypedDescriptor aProperty,
+                       bool* aFoundResult);
+
+  void DeleteInternal(const nsIFrame* aFrame, UntypedDescriptor aProperty);
+
+  // A helper union being used here rather than simple reinterpret_cast
+  // is because PropertyType<T> could be float, bool, uint8_t, etc.
+  // which do not have defined behavior for a direct cast.
+  template<typename T>
+  union ReinterpretHelper
+  {
+    void* ptr;
+    PropertyType<T> value;
+    static_assert(sizeof(PropertyType<T>) <= sizeof(void*),
+                  "size of the value must never be larger than a pointer");
+  };
+
   /**
    * Stores a property descriptor/value pair. It can also be used to
    * store an nsTArray of PropertyValues.
    */
   struct PropertyValue {
     PropertyValue() : mProperty(nullptr), mValue(nullptr) {}
-    PropertyValue(const FramePropertyDescriptor* aProperty, void* aValue)
+    PropertyValue(UntypedDescriptor aProperty, void* aValue)
       : mProperty(aProperty), mValue(aValue) {}
 
     bool IsArray() { return !mProperty && mValue; }
@@ -174,7 +306,7 @@ protected:
       return n;
     }
 
-    const FramePropertyDescriptor* mProperty;
+    UntypedDescriptor mProperty;
     void* mValue;
   };
 
@@ -187,10 +319,10 @@ protected:
     bool Equals(const PropertyValue& a, const PropertyValue& b) const {
       return a.mProperty == b.mProperty;
     }
-    bool Equals(const FramePropertyDescriptor* a, const PropertyValue& b) const {
+    bool Equals(UntypedDescriptor a, const PropertyValue& b) const {
       return a == b.mProperty;
     }
-    bool Equals(const PropertyValue& a, const FramePropertyDescriptor* b) const {
+    bool Equals(const PropertyValue& a, UntypedDescriptor b) const {
       return a.mProperty == b;
     }
   };
@@ -225,33 +357,39 @@ protected:
  */
 class FrameProperties {
 public:
+  template<typename T> using Descriptor = FramePropertyTable::Descriptor<T>;
+  template<typename T> using PropertyType = FramePropertyTable::PropertyType<T>;
+
   FrameProperties(FramePropertyTable* aTable, const nsIFrame* aFrame)
     : mTable(aTable), mFrame(aFrame) {}
 
-  void Set(const FramePropertyDescriptor* aProperty, void* aValue) const
+  template<typename T>
+  void Set(Descriptor<T> aProperty, PropertyType<T> aValue) const
   {
     mTable->Set(mFrame, aProperty, aValue);
   }
-  void* Get(const FramePropertyDescriptor* aProperty,
-            bool* aFoundResult = nullptr) const
+  template<typename T>
+  PropertyType<T> Get(Descriptor<T> aProperty,
+                      bool* aFoundResult = nullptr) const
   {
     return mTable->Get(mFrame, aProperty, aFoundResult);
   }
-  void* Remove(const FramePropertyDescriptor* aProperty,
-               bool* aFoundResult = nullptr) const
+  template<typename T>
+  PropertyType<T> Remove(Descriptor<T> aProperty,
+                         bool* aFoundResult = nullptr) const
   {
     return mTable->Remove(mFrame, aProperty, aFoundResult);
   }
-  void Delete(const FramePropertyDescriptor* aProperty)
+  template<typename T>
+  void Delete(Descriptor<T> aProperty)
   {
     mTable->Delete(mFrame, aProperty);
   }
-  // TenFourFox issue 493
-  bool Has(const FramePropertyDescriptor* aProperty)
+
+  template<typename T>
+  bool Has(Descriptor<T> aProperty) const
   {
-    bool foundResult;
-    (void)mTable->Get(mFrame, aProperty, &foundResult);
-    return foundResult;
+    return mTable->Has(mFrame, aProperty);
   }
 
 private:
diff --git a/layout/base/RestyleManager.cpp b/layout/base/RestyleManager.cpp
index 8784c95748..c2681387f6 100644
--- a/layout/base/RestyleManager.cpp
+++ b/layout/base/RestyleManager.cpp
@@ -642,7 +642,7 @@ RestyleManager::AddSubtreeToOverflowTracker(nsIFrame* aFrame)
   }
 }
 
-NS_DECLARE_FRAME_PROPERTY(ChangeListProperty, nullptr)
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(ChangeListProperty, bool)
 
 /**
  * Return true if aFrame's subtree has placeholders for out-of-flow content
@@ -735,8 +735,7 @@ RestyleManager::ProcessRestyledFrames(nsStyleChangeList& aChangeList)
     const nsStyleChangeData* changeData;
     aChangeList.ChangeAt(index, &changeData);
     if (changeData->mFrame) {
-      propTable->Set(changeData->mFrame, ChangeListProperty(),
-                     NS_INT32_TO_PTR(1));
+      propTable->Set(changeData->mFrame, ChangeListProperty(), true);
     }
   }
 
diff --git a/layout/base/RestyleTracker.h b/layout/base/RestyleTracker.h
index fa56cf9dfe..e2e7d94355 100644
--- a/layout/base/RestyleTracker.h
+++ b/layout/base/RestyleTracker.h
@@ -128,13 +128,9 @@ public:
         // Take a faster path that doesn't require unioning the overflow areas
         // of our children.
 
-#ifdef DEBUG
-        bool hasInitialOverflowPropertyApplied = false;
-        frame->Properties().Get(nsIFrame::DebugInitialOverflowPropertyApplied(),
-                                 &hasInitialOverflowPropertyApplied);
-        NS_ASSERTION(hasInitialOverflowPropertyApplied,
+        NS_ASSERTION(frame->Properties().Get(
+                       nsIFrame::DebugInitialOverflowPropertyApplied()),
                      "InitialOverflowProperty must be set first.");
-#endif
 
         nsOverflowAreas* overflow = 
           static_cast<nsOverflowAreas*>(frame->Properties().Get(nsIFrame::InitialOverflowProperty()));
diff --git a/layout/base/UnitTransforms.h b/layout/base/UnitTransforms.h
index 7446594739..b6e6a25504 100644
--- a/layout/base/UnitTransforms.h
+++ b/layout/base/UnitTransforms.h
@@ -47,7 +47,11 @@ enum class PixelCastJustification : uint8_t {
   LayoutDeviceIsScreenForTabDims,
   // A combination of LayoutDeviceIsScreenForBounds and
   // ScreenIsParentLayerForRoot, which is how we're using it.
-  LayoutDeviceIsParentLayerForRCDRSF
+  LayoutDeviceIsParentLayerForRCDRSF,
+  // Used to treat the product of AsyncTransformComponentMatrix objects
+  // as an AsyncTransformMatrix. See the definitions of these matrices in
+  // LayersTypes.h for details.
+  MultipleAsyncTransforms
 };
 
 template <class TargetUnits, class SourceUnits>
@@ -92,6 +96,19 @@ gfx::ScaleFactor<SourceUnits, NewTargetUnits> ViewTargetAs(
     PixelCastJustification) {
   return gfx::ScaleFactor<SourceUnits, NewTargetUnits>(aScaleFactor.scale);
 }
+// Unlike the other functions in this category, this function takes the
+// target matrix type, rather than its source and target unit types, as
+// the explicit template argument, so an example invocation is:
+//    ViewAs<ScreenToLayerMatrix4x4>(otherTypedMatrix, justification)
+// The reason is that if it took the source and target unit types as two
+// template arguments, there may be some confusion as to which is the
+// source and which is the target.
+template <class TargetMatrix, class SourceMatrixSourceUnits, class SourceMatrixTargetUnits>
+TargetMatrix ViewAs(
+    const gfx::Matrix4x4Typed<SourceMatrixSourceUnits, SourceMatrixTargetUnits>& aMatrix,
+    PixelCastJustification) {
+  return TargetMatrix::FromUnknownMatrix(aMatrix.ToUnknownMatrix());
+}
 
 // Convenience functions for casting untyped entities to typed entities.
 // Using these functions does not require a justification, but once we convert
diff --git a/layout/base/Units.h b/layout/base/Units.h
index 66dfe575fa..90cc41d9d8 100644
--- a/layout/base/Units.h
+++ b/layout/base/Units.h
@@ -28,6 +28,7 @@ struct IsPixel : FalseType {};
 struct CSSPixel;
 struct LayoutDevicePixel;
 struct LayerPixel;
+struct CSSTransformedLayerPixel;
 struct RenderTargetPixel;
 struct ScreenPixel;
 struct ParentLayerPixel;
@@ -36,6 +37,7 @@ struct DesktopPixel;
 template<> struct IsPixel<CSSPixel>          : TrueType {};
 template<> struct IsPixel<LayoutDevicePixel> : TrueType {};
 template<> struct IsPixel<LayerPixel>        : TrueType {};
+template<> struct IsPixel<CSSTransformedLayerPixel> : TrueType {};
 template<> struct IsPixel<RenderTargetPixel> : TrueType {};
 template<> struct IsPixel<ScreenPixel>       : TrueType {};
 template<> struct IsPixel<ParentLayerPixel>  : TrueType {};
@@ -77,6 +79,18 @@ typedef gfx::MarginTyped<LayerPixel> LayerMargin;
 typedef gfx::IntMarginTyped<LayerPixel> LayerIntMargin;
 typedef gfx::IntRegionTyped<LayerPixel> LayerIntRegion;
 
+typedef gfx::CoordTyped<CSSTransformedLayerPixel> CSSTransformedLayerCoord;
+typedef gfx::IntCoordTyped<CSSTransformedLayerPixel> CSSTransformedLayerIntCoord;
+typedef gfx::PointTyped<CSSTransformedLayerPixel> CSSTransformedLayerPoint;
+typedef gfx::IntPointTyped<CSSTransformedLayerPixel> CSSTransformedLayerIntPoint;
+typedef gfx::SizeTyped<CSSTransformedLayerPixel> CSSTransformedLayerSize;
+typedef gfx::IntSizeTyped<CSSTransformedLayerPixel> CSSTransformedLayerIntSize;
+typedef gfx::RectTyped<CSSTransformedLayerPixel> CSSTransformedLayerRect;
+typedef gfx::IntRectTyped<CSSTransformedLayerPixel> CSSTransformedLayerIntRect;
+typedef gfx::MarginTyped<CSSTransformedLayerPixel> CSSTransformedLayerMargin;
+typedef gfx::IntMarginTyped<CSSTransformedLayerPixel> CSSTransformedLayerIntMargin;
+typedef gfx::IntRegionTyped<CSSTransformedLayerPixel> CSSTransformedLayerIntRegion;
+
 typedef gfx::PointTyped<RenderTargetPixel> RenderTargetPoint;
 typedef gfx::IntPointTyped<RenderTargetPixel> RenderTargetIntPoint;
 typedef gfx::SizeTyped<RenderTargetPixel> RenderTargetSize;
@@ -340,6 +354,16 @@ struct LayoutDevicePixel {
 struct LayerPixel {
 };
 
+/*
+ * This is Layer coordinates with the Layer's CSS transform applied.
+ * It can be thought of as intermediate between LayerPixel and
+ * ParentLayerPixel, as further applying async transforms to this
+ * yields ParentLayerPixels.
+ */
+struct CSSTransformedLayerPixel {
+
+};
+
 /*
  * Layers are always composited to a render target. This unit
  * represents one pixel in the render target. Note that for the
diff --git a/layout/base/nsBidi.h b/layout/base/nsBidi.h
index 890fc273b1..3cd668b80e 100644
--- a/layout/base/nsBidi.h
+++ b/layout/base/nsBidi.h
@@ -428,8 +428,6 @@ struct LevState {
 class nsBidi
 {
 public:
-  typedef mozilla::FramePropertyDescriptor FramePropertyDescriptor;
-
   /** @brief Default constructor.
    *
    * The nsBidi object is initially empty. It is assigned
@@ -660,18 +658,18 @@ public:
    */
   nsresult WriteReverse(const char16_t *aSrc, int32_t aSrcLength, char16_t *aDest, uint16_t aOptions, int32_t *aDestSize);
 
-  NS_DECLARE_FRAME_PROPERTY(BaseLevelProperty, nullptr)
-  NS_DECLARE_FRAME_PROPERTY(EmbeddingLevelProperty, nullptr)
-  NS_DECLARE_FRAME_PROPERTY(ParagraphDepthProperty, nullptr)
+  NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(BaseLevelProperty, nsBidiLevel)
+  NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(EmbeddingLevelProperty, nsBidiLevel)
+  NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(ParagraphDepthProperty, uint8_t)
 
 #define NS_GET_BASE_LEVEL(frame) \
-NS_PTR_TO_INT32(frame->Properties().Get(nsBidi::BaseLevelProperty()))
+  frame->Properties().Get(nsBidi::BaseLevelProperty())
 
 #define NS_GET_EMBEDDING_LEVEL(frame) \
-NS_PTR_TO_INT32(frame->Properties().Get(nsBidi::EmbeddingLevelProperty()))
+  frame->Properties().Get(nsBidi::EmbeddingLevelProperty())
 
 #define NS_GET_PARAGRAPH_DEPTH(frame) \
-NS_PTR_TO_INT32(frame->Properties().Get(nsBidi::ParagraphDepthProperty()))
+  frame->Properties().Get(nsBidi::ParagraphDepthProperty())
 
 protected:
   friend class nsBidiPresUtils;
diff --git a/layout/base/nsBidiPresUtils.cpp b/layout/base/nsBidiPresUtils.cpp
index ff4f5ee941..721790f29a 100644
--- a/layout/base/nsBidiPresUtils.cpp
+++ b/layout/base/nsBidiPresUtils.cpp
@@ -796,11 +796,11 @@ nsBidiPresUtils::ResolveParagraph(nsBlockFrame* aBlockFrame,
           // Set the base level and embedding level of the current run even
           // on an empty frame. Otherwise frame reordering will not be correct.
           propTable->Set(frame, nsBidi::EmbeddingLevelProperty(),
-                         NS_INT32_TO_PTR(embeddingLevel));
+                         embeddingLevel);
           propTable->Set(frame, nsBidi::BaseLevelProperty(),
-                         NS_INT32_TO_PTR(aBpd->GetParaLevel()));
+                         aBpd->GetParaLevel());
           propTable->Set(frame, nsBidi::ParagraphDepthProperty(),
-                         NS_INT32_TO_PTR(aBpd->mParagraphDepth));
+                         aBpd->mParagraphDepth);
           continue;
         }
         int32_t start, end;
@@ -832,11 +832,11 @@ nsBidiPresUtils::ResolveParagraph(nsBlockFrame* aBlockFrame,
     }
     else {
       propTable->Set(frame, nsBidi::EmbeddingLevelProperty(),
-                     NS_INT32_TO_PTR(embeddingLevel));
+                     embeddingLevel);
       propTable->Set(frame, nsBidi::BaseLevelProperty(),
-                     NS_INT32_TO_PTR(aBpd->GetParaLevel()));
+                     aBpd->GetParaLevel());
       propTable->Set(frame, nsBidi::ParagraphDepthProperty(),
-                     NS_INT32_TO_PTR(aBpd->mParagraphDepth));
+                     aBpd->mParagraphDepth);
       if (isTextFrame) {
         if ( (runLength > 0) && (runLength < fragmentLength) ) {
           /*
@@ -1782,12 +1782,9 @@ nsBidiPresUtils::RemoveBidiContinuation(BidiParagraphData *aBpd,
                                         int32_t&        aOffset)
 {
   FrameProperties props = aFrame->Properties();
-  nsBidiLevel embeddingLevel =
-    (nsBidiLevel)NS_PTR_TO_INT32(props.Get(nsBidi::EmbeddingLevelProperty()));
-  nsBidiLevel baseLevel =
-    (nsBidiLevel)NS_PTR_TO_INT32(props.Get(nsBidi::BaseLevelProperty()));
-  uint8_t paragraphDepth = 
-    NS_PTR_TO_INT32(props.Get(nsBidi::ParagraphDepthProperty()));
+  nsBidiLevel embeddingLevel = props.Get(nsBidi::EmbeddingLevelProperty());
+  nsBidiLevel baseLevel = props.Get(nsBidi::BaseLevelProperty());
+  uint8_t paragraphDepth = props.Get(nsBidi::ParagraphDepthProperty());
 
   for (int32_t index = aFirstIndex + 1; index <= aLastIndex; index++) {
     nsIFrame* frame = aBpd->FrameAt(index);
@@ -1798,12 +1795,9 @@ nsBidiPresUtils::RemoveBidiContinuation(BidiParagraphData *aBpd,
       // Make the frame and its continuation ancestors fluid,
       // so they can be reused or deleted by normal reflow code
       FrameProperties frameProps = frame->Properties();
-      frameProps.Set(nsBidi::EmbeddingLevelProperty(),
-                     NS_INT32_TO_PTR(embeddingLevel));
-      frameProps.Set(nsBidi::BaseLevelProperty(),
-                     NS_INT32_TO_PTR(baseLevel));
-      frameProps.Set(nsBidi::ParagraphDepthProperty(),
-                     NS_INT32_TO_PTR(paragraphDepth));
+      frameProps.Set(nsBidi::EmbeddingLevelProperty(), embeddingLevel);
+      frameProps.Set(nsBidi::BaseLevelProperty(), baseLevel);
+      frameProps.Set(nsBidi::ParagraphDepthProperty(), paragraphDepth);
       frame->AddStateBits(NS_FRAME_IS_BIDI);
       while (frame) {
         nsIFrame* prev = frame->GetPrevContinuation();
diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 396ce7850d..c546137a9d 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -5950,13 +5950,11 @@ AddGenConPseudoToFrame(nsIFrame* aOwnerFrame, nsIContent* aContent)
   NS_ASSERTION(nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(aOwnerFrame),
                "property should only be set on first continuation/ib-sibling");
 
-  typedef nsAutoTArray<nsIContent*, 2> T;
-  const FramePropertyDescriptor* prop = nsIFrame::GenConProperty();
   FrameProperties props = aOwnerFrame->Properties();
-  T* value = static_cast<T*>(props.Get(prop));
+  nsIFrame::ContentArray* value = props.Get(nsIFrame::GenConProperty());
   if (!value) {
-    value = new T;
-    props.Set(prop, value);
+    value = new nsIFrame::ContentArray;
+    props.Set(nsIFrame::GenConProperty(), value);
   }
   value->AppendElement(aContent);
 }
diff --git a/layout/base/nsCSSRendering.cpp b/layout/base/nsCSSRendering.cpp
index 49a99eaac9..ade9410cd1 100644
--- a/layout/base/nsCSSRendering.cpp
+++ b/layout/base/nsCSSRendering.cpp
@@ -1006,7 +1006,7 @@ nsCSSRendering::PaintFocus(nsPresContext* aPresContext,
  * that function, except they're for a single coordinate / a single size
  * dimension. (so, x/width vs. y/height)
  */
-typedef nsStyleBackground::Position::PositionCoord PositionCoord;
+typedef nsStyleImageLayers::Position::PositionCoord PositionCoord;
 static void
 ComputeObjectAnchorCoord(const PositionCoord& aCoord,
                          const nscoord aOriginBounds,
@@ -1030,7 +1030,7 @@ ComputeObjectAnchorCoord(const PositionCoord& aCoord,
 
 void
 nsImageRenderer::ComputeObjectAnchorPoint(
-  const nsStyleBackground::Position& aPos,
+  const nsStyleImageLayers::Position& aPos,
   const nsSize& aOriginBounds,
   const nsSize& aImageSize,
   nsPoint* aTopLeft,
@@ -1750,11 +1750,11 @@ SetupDirtyRects(const nsRect& aBGClipArea, const nsRect& aCallerDirtyRect,
 }
 
 /* static */ void
-nsCSSRendering::GetBackgroundClip(const nsStyleBackground::Layer& aLayer,
+nsCSSRendering::GetImageLayerClip(const nsStyleImageLayers::Layer& aLayer,
                                   nsIFrame* aForFrame, const nsStyleBorder& aBorder,
                                   const nsRect& aBorderArea, const nsRect& aCallerDirtyRect,
                                   bool aWillPaintBorder, nscoord aAppUnitsPerPixel,
-                                  /* out */ BackgroundClipState* aClipState)
+                                  /* out */ ImageLayerClipState* aClipState)
 {
   // Compute the outermost boundary of the area that might be painted.
   // Same coordinate space as aBorderArea.
@@ -1769,12 +1769,12 @@ nsCSSRendering::GetBackgroundClip(const nsStyleBackground::Layer& aLayer,
 
   bool isSolidBorder =
       aWillPaintBorder && IsOpaqueBorder(aBorder);
-  if (isSolidBorder && backgroundClip == NS_STYLE_BG_CLIP_BORDER) {
+  if (isSolidBorder && backgroundClip == NS_STYLE_IMAGELAYER_CLIP_BORDER) {
     // If we have rounded corners, we need to inflate the background
     // drawing area a bit to avoid seams between the border and
     // background.
     backgroundClip = haveRoundedCorners ?
-      NS_STYLE_BG_CLIP_MOZ_ALMOST_PADDING : NS_STYLE_BG_CLIP_PADDING;
+      NS_STYLE_IMAGELAYER_CLIP_MOZ_ALMOST_PADDING : NS_STYLE_IMAGELAYER_CLIP_PADDING;
   }
 
   aClipState->mBGClipArea = clipBorderArea;
@@ -1782,7 +1782,7 @@ nsCSSRendering::GetBackgroundClip(const nsStyleBackground::Layer& aLayer,
   aClipState->mCustomClip = false;
 
   if (aForFrame->GetType() == nsGkAtoms::scrollFrame &&
-      NS_STYLE_BG_ATTACHMENT_LOCAL == aLayer.mAttachment) {
+      NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL == aLayer.mAttachment) {
     // As of this writing, this is still in discussion in the CSS Working Group
     // http://lists.w3.org/Archives/Public/www-style/2013Jul/0250.html
 
@@ -1790,7 +1790,7 @@ nsCSSRendering::GetBackgroundClip(const nsStyleBackground::Layer& aLayer,
     // but the background is also clipped at a non-scrolling 'padding-box'
     // like the content. (See below.)
     // Therefore, only 'content-box' makes a difference here.
-    if (backgroundClip == NS_STYLE_BG_CLIP_CONTENT) {
+    if (backgroundClip == NS_STYLE_IMAGELAYER_CLIP_CONTENT) {
       nsIScrollableFrame* scrollableFrame = do_QueryFrame(aForFrame);
       // Clip at a rectangle attached to the scrolled content.
       aClipState->mHasAdditionalBGClipArea = true;
@@ -1810,12 +1810,12 @@ nsCSSRendering::GetBackgroundClip(const nsStyleBackground::Layer& aLayer,
 
     // Also clip at a non-scrolling, rounded-corner 'padding-box',
     // same as the scrolled content because of the 'overflow' property.
-    backgroundClip = NS_STYLE_BG_CLIP_PADDING;
+    backgroundClip = NS_STYLE_IMAGELAYER_CLIP_PADDING;
   }
 
-  if (backgroundClip != NS_STYLE_BG_CLIP_BORDER) {
+  if (backgroundClip != NS_STYLE_IMAGELAYER_CLIP_BORDER) {
     nsMargin border = aForFrame->GetUsedBorder();
-    if (backgroundClip == NS_STYLE_BG_CLIP_MOZ_ALMOST_PADDING) {
+    if (backgroundClip == NS_STYLE_IMAGELAYER_CLIP_MOZ_ALMOST_PADDING) {
       // Reduce |border| by 1px (device pixels) on all sides, if
       // possible, so that we don't get antialiasing seams between the
       // background and border.
@@ -1823,8 +1823,8 @@ nsCSSRendering::GetBackgroundClip(const nsStyleBackground::Layer& aLayer,
       border.right = std::max(0, border.right - aAppUnitsPerPixel);
       border.bottom = std::max(0, border.bottom - aAppUnitsPerPixel);
       border.left = std::max(0, border.left - aAppUnitsPerPixel);
-    } else if (backgroundClip != NS_STYLE_BG_CLIP_PADDING) {
-      NS_ASSERTION(backgroundClip == NS_STYLE_BG_CLIP_CONTENT,
+    } else if (backgroundClip != NS_STYLE_IMAGELAYER_CLIP_PADDING) {
+      NS_ASSERTION(backgroundClip == NS_STYLE_IMAGELAYER_CLIP_CONTENT,
                    "unexpected background-clip");
       border += aForFrame->GetUsedPadding();
     }
@@ -1857,7 +1857,7 @@ nsCSSRendering::GetBackgroundClip(const nsStyleBackground::Layer& aLayer,
 }
 
 static void
-SetupBackgroundClip(nsCSSRendering::BackgroundClipState& aClipState,
+SetupImageLayerClip(nsCSSRendering::ImageLayerClipState& aClipState,
                     gfxContext *aCtx, nscoord aAppUnitsPerPixel,
                     gfxContextAutoSaveRestore* aAutoSR)
 {
@@ -1916,7 +1916,7 @@ SetupBackgroundClip(nsCSSRendering::BackgroundClipState& aClipState,
 }
 
 static void
-DrawBackgroundColor(nsCSSRendering::BackgroundClipState& aClipState,
+DrawBackgroundColor(nsCSSRendering::ImageLayerClipState& aClipState,
                     gfxContext *aCtx, nscoord aAppUnitsPerPixel)
 {
   if (aClipState.mDirtyRectGfx.IsEmpty()) {
@@ -2009,11 +2009,11 @@ nsCSSRendering::DetermineBackgroundColor(nsPresContext* aPresContext,
   }
 
   // We can skip painting the background color if a background image is opaque.
-  nsStyleBackground::Repeat repeat = bg->BottomLayer().mRepeat;
-  bool xFullRepeat = repeat.mXRepeat == NS_STYLE_BG_REPEAT_REPEAT ||
-                     repeat.mXRepeat == NS_STYLE_BG_REPEAT_ROUND;
-  bool yFullRepeat = repeat.mYRepeat == NS_STYLE_BG_REPEAT_REPEAT ||
-                     repeat.mYRepeat == NS_STYLE_BG_REPEAT_ROUND;
+  nsStyleImageLayers::Repeat repeat = bg->BottomLayer().mRepeat;
+  bool xFullRepeat = repeat.mXRepeat == NS_STYLE_IMAGELAYER_REPEAT_REPEAT ||
+                     repeat.mXRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND;
+  bool yFullRepeat = repeat.mYRepeat == NS_STYLE_IMAGELAYER_REPEAT_REPEAT ||
+                     repeat.mYRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND;
   if (aDrawBackgroundColor &&
       xFullRepeat && yFullRepeat &&
       bg->BottomLayer().mImage.IsOpaque() &&
@@ -2906,9 +2906,9 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
                                              drawBackgroundImage,
                                              drawBackgroundColor);
 
+  const nsStyleImageLayers& layers = aBackgroundSC->StyleBackground()->mLayers;
   // If we're drawing a specific layer, we don't want to draw the
   // background color.
-  const nsStyleBackground *bg = aBackgroundSC->StyleBackground();
   if (drawBackgroundColor && aLayer >= 0) {
     drawBackgroundColor = false;
   }
@@ -2935,7 +2935,7 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
   // taking the intersection breaks reftests/bugs/403249-1[ab].)
   gfxContext* ctx = aRenderingContext.ThebesContext();
   nscoord appUnitsPerPixel = aPresContext->AppUnitsPerDevPixel();
-  BackgroundClipState clipState;
+  ImageLayerClipState clipState;
   if (aBGClipRect) {
     clipState.mBGClipArea = *aBGClipRect;
     clipState.mCustomClip = true;
@@ -2943,9 +2943,10 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
     SetupDirtyRects(clipState.mBGClipArea, aDirtyRect, appUnitsPerPixel,
                     &clipState.mDirtyRect, &clipState.mDirtyRectGfx);
   } else {
-    GetBackgroundClip(bg->BottomLayer(),
+    GetImageLayerClip(layers.BottomLayer(),
                       aForFrame, aBorder, aBorderArea,
-                      aDirtyRect, (aFlags & PAINTBG_WILL_PAINT_BORDER), appUnitsPerPixel,
+                      aDirtyRect, (aFlags & PAINTBG_WILL_PAINT_BORDER),
+                      appUnitsPerPixel,
                       &clipState);
   }
 
@@ -2967,7 +2968,7 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
     return DrawResult::SUCCESS;
   }
 
-  if (bg->mImageCount < 1) {
+  if (layers.mImageCount < 1) {
     // Return if there are no background layers, all work from this point
     // onwards happens iteratively on these.
     return DrawResult::SUCCESS;
@@ -2977,16 +2978,16 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
   int32_t startLayer = aLayer;
   int32_t nLayers = 1;
   if (startLayer < 0) {
-    startLayer = (int32_t)bg->mImageCount - 1;
-    nLayers = bg->mImageCount;
+    startLayer = (int32_t)layers.mImageCount - 1;
+    nLayers = layers.mImageCount;
   }
 
   // Ensure we get invalidated for loads of the image.  We need to do
   // this here because this might be the only code that knows about the
   // association of the style data with the frame.
   if (aBackgroundSC != aForFrame->StyleContext()) {
-    NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT_WITH_RANGE(i, bg, startLayer, nLayers) {
-      aForFrame->AssociateImage(bg->mLayers[i].mImage, aPresContext);
+    NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT_WITH_RANGE(i, layers, startLayer, nLayers) {
+      aForFrame->AssociateImage(layers.mLayers[i].mImage, aPresContext);
     }
   }
 
@@ -2998,24 +2999,24 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
 
   if (drawBackgroundImage) {
     bool clipSet = false;
-    uint8_t currentBackgroundClip = NS_STYLE_BG_CLIP_BORDER;
-    NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT_WITH_RANGE(i, bg, bg->mImageCount - 1,
-                                                              nLayers + (bg->mImageCount -
-                                                                         startLayer - 1)) {
-      const nsStyleBackground::Layer &layer = bg->mLayers[i];
+    uint8_t currentBackgroundClip = NS_STYLE_IMAGELAYER_CLIP_BORDER;
+    NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT_WITH_RANGE(i, layers, layers.mImageCount - 1,
+                                                         nLayers + (layers.mImageCount -
+                                                         startLayer - 1)) {
+      const nsStyleImageLayers::Layer& layer = layers.mLayers[i];
       if (!aBGClipRect) {
         if (currentBackgroundClip != layer.mClip || !clipSet) {
           currentBackgroundClip = layer.mClip;
           // If clipSet is false that means this is the bottom layer and we
-          // already called GetBackgroundClip above and it stored its results
+          // already called GetImageLayerClip above and it stored its results
           // in clipState.
           if (clipSet) {
             autoSR.Restore(); // reset the previous one
-            GetBackgroundClip(layer, aForFrame,
+            GetImageLayerClip(layer, aForFrame,
                               aBorder, aBorderArea, aDirtyRect, (aFlags & PAINTBG_WILL_PAINT_BORDER),
                               appUnitsPerPixel, &clipState);
           }
-          SetupBackgroundClip(clipState, ctx, appUnitsPerPixel, &autoSR);
+          SetupImageLayerClip(clipState, ctx, appUnitsPerPixel, &autoSR);
           clipSet = true;
           if (!clipBorderArea.IsEqualEdges(aBorderArea)) {
             // We're drawing the background for the joined continuation boxes
@@ -3031,10 +3032,9 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
       }
       if ((aLayer < 0 || i == (uint32_t)startLayer) &&
           !clipState.mDirtyRectGfx.IsEmpty()) {
-        nsBackgroundLayerState state = PrepareBackgroundLayer(aPresContext, aForFrame,
+        nsBackgroundLayerState state = PrepareImageLayer(aPresContext, aForFrame,
             aFlags, paintBorderArea, clipState.mBGClipArea, layer);
         result &= state.mImageRenderer.PrepareResult();
-
         if (!state.mFillArea.IsEmpty()) {
           if (state.mCompositionOp != CompositionOp::OP_OVER) {
             NS_ASSERTION(ctx->CurrentOp() == CompositionOp::OP_OVER,
@@ -3072,10 +3072,10 @@ IsTransformed(nsIFrame* aForFrame, nsIFrame* aTopFrame)
 }
 
 nsRect
-nsCSSRendering::ComputeBackgroundPositioningArea(nsPresContext* aPresContext,
+nsCSSRendering::ComputeImageLayerPositioningArea(nsPresContext* aPresContext,
                                                  nsIFrame* aForFrame,
                                                  const nsRect& aBorderArea,
-                                                 const nsStyleBackground::Layer& aLayer,
+                                                 const nsStyleImageLayers::Layer& aLayer,
                                                  nsIFrame** aAttachedToFrame)
 {
   // Compute background origin area relative to aBorderArea now as we may need
@@ -3085,7 +3085,7 @@ nsCSSRendering::ComputeBackgroundPositioningArea(nsPresContext* aPresContext,
   nsIAtom* frameType = aForFrame->GetType();
   nsIFrame* geometryFrame = aForFrame;
   if (MOZ_UNLIKELY(frameType == nsGkAtoms::scrollFrame &&
-                   NS_STYLE_BG_ATTACHMENT_LOCAL == aLayer.mAttachment)) {
+                   NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL == aLayer.mAttachment)) {
     nsIScrollableFrame* scrollableFrame = do_QueryFrame(aForFrame);
     bgPositioningArea = nsRect(
       scrollableFrame->GetScrolledFrame()->GetPosition()
@@ -3095,16 +3095,16 @@ nsCSSRendering::ComputeBackgroundPositioningArea(nsPresContext* aPresContext,
     // The ScrolledRect’s size does not include the borders or scrollbars,
     // reverse the handling of background-origin
     // compared to the common case below.
-    if (aLayer.mOrigin == NS_STYLE_BG_ORIGIN_BORDER) {
+    if (aLayer.mOrigin == NS_STYLE_IMAGELAYER_ORIGIN_BORDER) {
       nsMargin border = geometryFrame->GetUsedBorder();
       border.ApplySkipSides(geometryFrame->GetSkipSides());
       bgPositioningArea.Inflate(border);
       bgPositioningArea.Inflate(scrollableFrame->GetActualScrollbarSizes());
-    } else if (aLayer.mOrigin != NS_STYLE_BG_ORIGIN_PADDING) {
+    } else if (aLayer.mOrigin != NS_STYLE_IMAGELAYER_ORIGIN_PADDING) {
       nsMargin padding = geometryFrame->GetUsedPadding();
       padding.ApplySkipSides(geometryFrame->GetSkipSides());
       bgPositioningArea.Deflate(padding);
-      NS_ASSERTION(aLayer.mOrigin == NS_STYLE_BG_ORIGIN_CONTENT,
+      NS_ASSERTION(aLayer.mOrigin == NS_STYLE_IMAGELAYER_ORIGIN_CONTENT,
                    "unknown background-origin value");
     }
     *aAttachedToFrame = aForFrame;
@@ -3126,18 +3126,18 @@ nsCSSRendering::ComputeBackgroundPositioningArea(nsPresContext* aPresContext,
 
   // Background images are tiled over the 'background-clip' area
   // but the origin of the tiling is based on the 'background-origin' area
-  if (aLayer.mOrigin != NS_STYLE_BG_ORIGIN_BORDER && geometryFrame) {
+  if (aLayer.mOrigin != NS_STYLE_IMAGELAYER_ORIGIN_BORDER && geometryFrame) {
     nsMargin border = geometryFrame->GetUsedBorder();
-    if (aLayer.mOrigin != NS_STYLE_BG_ORIGIN_PADDING) {
+    if (aLayer.mOrigin != NS_STYLE_IMAGELAYER_ORIGIN_PADDING) {
       border += geometryFrame->GetUsedPadding();
-      NS_ASSERTION(aLayer.mOrigin == NS_STYLE_BG_ORIGIN_CONTENT,
+      NS_ASSERTION(aLayer.mOrigin == NS_STYLE_IMAGELAYER_ORIGIN_CONTENT,
                    "unknown background-origin value");
     }
     bgPositioningArea.Deflate(border);
   }
 
   nsIFrame* attachedToFrame = aForFrame;
-  if (NS_STYLE_BG_ATTACHMENT_FIXED == aLayer.mAttachment) {
+  if (NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED == aLayer.mAttachment) {
     // If it's a fixed background attachment, then the image is placed
     // relative to the viewport, which is the area of the root frame
     // in a screen context or the page content frame in a print context.
@@ -3194,16 +3194,16 @@ ComputeRoundedSize(nscoord aCurrentSize, nscoord aPositioningSize)
 static nsSize
 ComputeDrawnSizeForBackground(const CSSSizeOrRatio& aIntrinsicSize,
                               const nsSize& aBgPositioningArea,
-                              const nsStyleBackground::Size& aLayerSize,
+                              const nsStyleImageLayers::Size& aLayerSize,
                               uint8_t aXRepeat, uint8_t aYRepeat)
 {
   nsSize imageSize;
   
   // Size is dictated by cover or contain rules.
-  if (aLayerSize.mWidthType == nsStyleBackground::Size::eContain ||
-      aLayerSize.mWidthType == nsStyleBackground::Size::eCover) {
+  if (aLayerSize.mWidthType == nsStyleImageLayers::Size::eContain ||
+      aLayerSize.mWidthType == nsStyleImageLayers::Size::eCover) {
     nsImageRenderer::FitType fitType =
-      aLayerSize.mWidthType == nsStyleBackground::Size::eCover
+      aLayerSize.mWidthType == nsStyleImageLayers::Size::eCover
         ? nsImageRenderer::COVER
         : nsImageRenderer::CONTAIN;
     imageSize = nsImageRenderer::ComputeConstrainedSize(aBgPositioningArea,
@@ -3212,11 +3212,11 @@ ComputeDrawnSizeForBackground(const CSSSizeOrRatio& aIntrinsicSize,
   } else {
     // No cover/contain constraint, use default algorithm.
     CSSSizeOrRatio specifiedSize;
-    if (aLayerSize.mWidthType == nsStyleBackground::Size::eLengthPercentage) {
+    if (aLayerSize.mWidthType == nsStyleImageLayers::Size::eLengthPercentage) {
       specifiedSize.SetWidth(
         aLayerSize.ResolveWidthLengthPercentage(aBgPositioningArea));
     }
-    if (aLayerSize.mHeightType == nsStyleBackground::Size::eLengthPercentage) {
+    if (aLayerSize.mHeightType == nsStyleImageLayers::Size::eLengthPercentage) {
       specifiedSize.SetHeight(
         aLayerSize.ResolveHeightLengthPercentage(aBgPositioningArea));
     }
@@ -3233,15 +3233,15 @@ ComputeDrawnSizeForBackground(const CSSSizeOrRatio& aIntrinsicSize,
   // "If 'background-repeat' is 'round' for one dimension only and if 'background-size'
   //  is 'auto' for the other dimension, then there is a third step: that other dimension
   //  is scaled so that the original aspect ratio is restored."
-  bool isRepeatRoundInBothDimensions = aXRepeat == NS_STYLE_BG_REPEAT_ROUND &&
-                                       aYRepeat == NS_STYLE_BG_REPEAT_ROUND;
+  bool isRepeatRoundInBothDimensions = aXRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND &&
+                                       aYRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND;
 
   // Calculate the rounded size only if the background-size computation
   // returned a correct size for the image.
-  if (imageSize.width && aXRepeat == NS_STYLE_BG_REPEAT_ROUND) {
+  if (imageSize.width && aXRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND) {
     imageSize.width = ComputeRoundedSize(imageSize.width, aBgPositioningArea.width);
     if (!isRepeatRoundInBothDimensions &&
-        aLayerSize.mHeightType == nsStyleBackground::Size::DimensionType::eAuto) {
+        aLayerSize.mHeightType == nsStyleImageLayers::Size::DimensionType::eAuto) {
       // Restore intrinsic rato
       if (aIntrinsicSize.mRatio.width) {
         float scale = float(aIntrinsicSize.mRatio.height) / aIntrinsicSize.mRatio.width;
@@ -3252,10 +3252,10 @@ ComputeDrawnSizeForBackground(const CSSSizeOrRatio& aIntrinsicSize,
 
   // Calculate the rounded size only if the background-size computation
   // returned a correct size for the image.
-  if (imageSize.height && aYRepeat == NS_STYLE_BG_REPEAT_ROUND) {
+  if (imageSize.height && aYRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND) {
     imageSize.height = ComputeRoundedSize(imageSize.height, aBgPositioningArea.height);
     if (!isRepeatRoundInBothDimensions &&
-        aLayerSize.mWidthType == nsStyleBackground::Size::DimensionType::eAuto) {
+        aLayerSize.mWidthType == nsStyleImageLayers::Size::DimensionType::eAuto) {
       // Restore intrinsic rato
       if (aIntrinsicSize.mRatio.height) {
         float scale = float(aIntrinsicSize.mRatio.width) / aIntrinsicSize.mRatio.height;
@@ -3285,26 +3285,28 @@ ComputeSpacedRepeatSize(nscoord aImageDimension,
 }
 
 nsBackgroundLayerState
-nsCSSRendering::PrepareBackgroundLayer(nsPresContext* aPresContext,
-                                       nsIFrame* aForFrame,
-                                       uint32_t aFlags,
-                                       const nsRect& aBorderArea,
-                                       const nsRect& aBGClipRect,
-                                       const nsStyleBackground::Layer& aLayer)
+nsCSSRendering::PrepareImageLayer(nsPresContext* aPresContext,
+                                  nsIFrame* aForFrame,
+                                  uint32_t aFlags,
+                                  const nsRect& aBorderArea,
+                                  const nsRect& aBGClipRect,
+                                  const nsStyleImageLayers::Layer& aLayer)
 {
   /*
-   * The properties we need to keep in mind when drawing background
+   * The properties we need to keep in mind when drawing style image
    * layers are:
    *
-   *   background-image
-   *   background-repeat
+   *   background-image/ mask-image
+   *   background-repeat/ mask-repeat
    *   background-attachment
-   *   background-position
-   *   background-clip
-   *   background-origin
-   *   background-size
+   *   background-position/ mask-position
+   *   background-clip/ mask-clip
+   *   background-origin/ mask-origin
+   *   background-size/ mask-size
    *   background-blend-mode
    *   box-decoration-break
+   *   mask-mode
+   *   mask-composite
    *
    * (background-color applies to the entire element and not to individual
    * layers, so it is irrelevant to this method.)
@@ -3312,39 +3314,45 @@ nsCSSRendering::PrepareBackgroundLayer(nsPresContext* aPresContext,
    * These properties have the following dependencies upon each other when
    * determining rendering:
    *
-   *   background-image
+   *   background-image/ mask-image
    *     no dependencies
-   *   background-repeat
+   *   background-repeat/ mask-repeat
    *     no dependencies
    *   background-attachment
    *     no dependencies
-   *   background-position
-   *     depends upon background-size (for the image's scaled size) and
-   *     background-break (for the background positioning area)
-   *   background-clip
+   *   background-position/ mask-position
+   *     depends upon background-size/mask-size (for the image's scaled size)
+   *     and background-break (for the background positioning area)
+   *   background-clip/ mask-clip
    *     no dependencies
-   *   background-origin
+   *   background-origin/ mask-origin
    *     depends upon background-attachment (only in the case where that value
    *     is 'fixed')
-   *   background-size
+   *   background-size/ mask-size
    *     depends upon box-decoration-break (for the background positioning area
    *     for resolving percentages), background-image (for the image's intrinsic
    *     size), background-repeat (if that value is 'round'), and
    *     background-origin (for the background painting area, when
    *     background-repeat is 'round')
+   *   background-blend-mode
+   *     no dependencies
+   *   mask-mode
+   *     no dependencies
+   *   mask-composite
+   *     no dependencies
    *   box-decoration-break
    *     no dependencies
    *
    * As a result of only-if dependencies we don't strictly do a topological
    * sort of the above properties when processing, but it's pretty close to one:
    *
-   *   background-clip (by caller)
-   *   background-image
-   *   box-decoration-break, background-origin
+   *   background-clip/mask-clip (by caller)
+   *   background-image/ mask-image
+   *   box-decoration-break, background-origin/ mask origin
    *   background-attachment (postfix for background-origin if 'fixed')
-   *   background-size
-   *   background-position
-   *   background-repeat
+   *   background-size/ mask-size
+   *   background-position/ mask-position
+   *   background-repeat/ mask-repeat
    */
 
   uint32_t irFlags = 0;
@@ -3366,7 +3374,7 @@ nsCSSRendering::PrepareBackgroundLayer(nsPresContext* aPresContext,
   // Compute background origin area relative to aBorderArea now as we may need
   // it to compute the effective image size for a CSS gradient.
   nsRect bgPositioningArea =
-    ComputeBackgroundPositioningArea(aPresContext, aForFrame, aBorderArea,
+    ComputeImageLayerPositioningArea(aPresContext, aForFrame, aBorderArea,
                                      aLayer, &attachedToFrame);
 
   // For background-attachment:fixed backgrounds, we'll limit the area
@@ -3378,7 +3386,7 @@ nsCSSRendering::PrepareBackgroundLayer(nsPresContext* aPresContext,
   // relative to aBorderArea.TopLeft() (which is where the top-left
   // of aForFrame's border-box will be rendered)
   nsPoint imageTopLeft;
-  if (NS_STYLE_BG_ATTACHMENT_FIXED == aLayer.mAttachment) {
+  if (NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED == aLayer.mAttachment) {
     if ((aFlags & nsCSSRendering::PAINTBG_TO_WINDOW) &&
         !IsTransformed(aForFrame, attachedToFrame)) {
       // Clip background-attachment:fixed backgrounds to the viewport, if we're
@@ -3418,25 +3426,25 @@ nsCSSRendering::PrepareBackgroundLayer(nsPresContext* aPresContext,
                                             bgPositionSize, imageSize,
                                             &imageTopLeft, &state.mAnchor);
   state.mRepeatSize = imageSize;
-  if (repeatX == NS_STYLE_BG_REPEAT_SPACE) {
+  if (repeatX == NS_STYLE_IMAGELAYER_REPEAT_SPACE) {
     state.mRepeatSize.width = ComputeSpacedRepeatSize(imageSize.width,
                                                       bgPositionSize.width);
     if (state.mRepeatSize.width > imageSize.width) {
       imageTopLeft.x = 0;
       state.mAnchor.x = 0;
     } else {
-      repeatX = NS_STYLE_BG_REPEAT_NO_REPEAT;
+      repeatX = NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT;
     }
   }
 
-  if (repeatY == NS_STYLE_BG_REPEAT_SPACE) {
+  if (repeatY == NS_STYLE_IMAGELAYER_REPEAT_SPACE) {
     state.mRepeatSize.height = ComputeSpacedRepeatSize(imageSize.height,
                                                        bgPositionSize.height);
     if (state.mRepeatSize.height > imageSize.height) {
       imageTopLeft.y = 0;
       state.mAnchor.y = 0;
     } else {
-      repeatY = NS_STYLE_BG_REPEAT_NO_REPEAT;
+      repeatY = NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT;
     }
   }
 
@@ -3447,16 +3455,16 @@ nsCSSRendering::PrepareBackgroundLayer(nsPresContext* aPresContext,
   state.mFillArea = state.mDestArea;
 
   ExtendMode repeatMode = ExtendMode::CLAMP;
-  if (repeatX == NS_STYLE_BG_REPEAT_REPEAT ||
-      repeatX == NS_STYLE_BG_REPEAT_ROUND ||
-      repeatX == NS_STYLE_BG_REPEAT_SPACE) {
+  if (repeatX == NS_STYLE_IMAGELAYER_REPEAT_REPEAT ||
+      repeatX == NS_STYLE_IMAGELAYER_REPEAT_ROUND ||
+      repeatX == NS_STYLE_IMAGELAYER_REPEAT_SPACE) {
     state.mFillArea.x = bgClipRect.x;
     state.mFillArea.width = bgClipRect.width;
     repeatMode = ExtendMode::REPEAT_X;
   }
-  if (repeatY == NS_STYLE_BG_REPEAT_REPEAT ||
-      repeatY == NS_STYLE_BG_REPEAT_ROUND ||
-      repeatY == NS_STYLE_BG_REPEAT_SPACE) {
+  if (repeatY == NS_STYLE_IMAGELAYER_REPEAT_REPEAT ||
+      repeatY == NS_STYLE_IMAGELAYER_REPEAT_ROUND ||
+      repeatY == NS_STYLE_IMAGELAYER_REPEAT_SPACE) {
     state.mFillArea.y = bgClipRect.y;
     state.mFillArea.height = bgClipRect.height;
 
@@ -3485,14 +3493,14 @@ nsCSSRendering::GetBackgroundLayerRect(nsPresContext* aPresContext,
                                        nsIFrame* aForFrame,
                                        const nsRect& aBorderArea,
                                        const nsRect& aClipRect,
-                                       const nsStyleBackground::Layer& aLayer,
+                                       const nsStyleImageLayers::Layer& aLayer,
                                        uint32_t aFlags)
 {
   Sides skipSides = aForFrame->GetSkipSides();
   nsRect borderArea =
     ::BoxDecorationRectForBackground(aForFrame, aBorderArea, skipSides);
   nsBackgroundLayerState state =
-      PrepareBackgroundLayer(aPresContext, aForFrame, aFlags, borderArea,
+      PrepareImageLayer(aPresContext, aForFrame, aFlags, borderArea,
                              aClipRect, aLayer);
   return state.mFillArea;
 }
@@ -4990,7 +4998,7 @@ nsImageRenderer::ComputeIntrinsicSize()
       //     and that element's ratio, if it matches.  If it doesn't match, it
       //     should have no width/height or ratio.  See element() in CSS images:
       //     <http://dev.w3.org/csswg/css-images-4/#element-notation>.
-      //     Make sure to change nsStyleBackground::Size::DependsOnFrameSize
+      //     Make sure to change nsStyleImageLayers::Size::DependsOnFrameSize
       //     when fixing this!
       if (mPaintServerFrame) {
         // SVG images have no intrinsic size
diff --git a/layout/base/nsCSSRendering.h b/layout/base/nsCSSRendering.h
index 8a731b0cee..ce3996ea40 100644
--- a/layout/base/nsCSSRendering.h
+++ b/layout/base/nsCSSRendering.h
@@ -175,7 +175,7 @@ public:
    *
    * Points are returned relative to aOriginBounds.
    */
-  static void ComputeObjectAnchorPoint(const nsStyleBackground::Position& aPos,
+  static void ComputeObjectAnchorPoint(const nsStyleImageLayers::Position& aPos,
                                        const nsSize& aOriginBounds,
                                        const nsSize& aImageSize,
                                        nsPoint* aTopLeft,
@@ -306,7 +306,7 @@ private:
 /**
  * A struct representing all the information needed to paint a background
  * image to some target, taking into account all CSS background-* properties.
- * See PrepareBackgroundLayer.
+ * See PrepareImageLayer.
  */
 struct nsBackgroundLayerState {
   typedef mozilla::gfx::CompositionOp CompositionOp;
@@ -327,19 +327,19 @@ struct nsBackgroundLayerState {
   /**
    * A rectangle that one copy of the image tile is mapped onto. Same
    * coordinate system as aBorderArea/aBGClipRect passed into
-   * PrepareBackgroundLayer.
+   * PrepareImageLayer.
    */
   nsRect mDestArea;
   /**
    * The actual rectangle that should be filled with (complete or partial)
    * image tiles. Same coordinate system as aBorderArea/aBGClipRect passed into
-   * PrepareBackgroundLayer.
+   * PrepareImageLayer.
    */
   nsRect mFillArea;
   /**
    * The anchor point that should be snapped to a pixel corner. Same
    * coordinate system as aBorderArea/aBGClipRect passed into
-   * PrepareBackgroundLayer.
+   * PrepareImageLayer.
    */
   nsPoint mAnchor;
   /**
@@ -537,21 +537,21 @@ struct nsCSSRendering {
                            bool& aDrawBackgroundColor);
 
   static nsRect
-  ComputeBackgroundPositioningArea(nsPresContext* aPresContext,
+  ComputeImageLayerPositioningArea(nsPresContext* aPresContext,
                                    nsIFrame* aForFrame,
                                    const nsRect& aBorderArea,
-                                   const nsStyleBackground::Layer& aLayer,
+                                   const nsStyleImageLayers::Layer& aLayer,
                                    nsIFrame** aAttachedToFrame);
 
   static nsBackgroundLayerState
-  PrepareBackgroundLayer(nsPresContext* aPresContext,
-                         nsIFrame* aForFrame,
-                         uint32_t aFlags,
-                         const nsRect& aBorderArea,
-                         const nsRect& aBGClipRect,
-                         const nsStyleBackground::Layer& aLayer);
+  PrepareImageLayer(nsPresContext* aPresContext,
+                    nsIFrame* aForFrame,
+                    uint32_t aFlags,
+                    const nsRect& aBorderArea,
+                    const nsRect& aBGClipRect,
+                    const nsStyleImageLayers::Layer& aLayer);
 
-  struct BackgroundClipState {
+  struct ImageLayerClipState {
     nsRect mBGClipArea;  // Affected by mClippedRadii
     nsRect mAdditionalBGClipArea;  // Not affected by mClippedRadii
     nsRect mDirtyRect;
@@ -568,11 +568,11 @@ struct nsCSSRendering {
   };
 
   static void
-  GetBackgroundClip(const nsStyleBackground::Layer& aLayer,
-                    nsIFrame* aForFrame, const nsStyleBorder& aBorder, const nsRect& aBorderArea,
-                    const nsRect& aCallerDirtyRect, bool aWillPaintBorder,
-                    nscoord aAppUnitsPerPixel,
-                    /* out */ BackgroundClipState* aClipState);
+  GetImageLayerClip(const nsStyleImageLayers::Layer& aLayer,
+                    nsIFrame* aForFrame, const nsStyleBorder& aBorder,
+                    const nsRect& aBorderArea, const nsRect& aCallerDirtyRect,
+                    bool aWillPaintBorder, nscoord aAppUnitsPerPixel,
+                    /* out */ ImageLayerClipState* aClipState);
 
   /**
    * Render the background for an element using css rendering rules
@@ -632,7 +632,7 @@ struct nsCSSRendering {
                                        nsIFrame* aForFrame,
                                        const nsRect& aBorderArea,
                                        const nsRect& aClipRect,
-                                       const nsStyleBackground::Layer& aLayer,
+                                       const nsStyleImageLayers::Layer& aLayer,
                                        uint32_t aFlags);
 
   /**
diff --git a/layout/base/nsDisplayList.cpp b/layout/base/nsDisplayList.cpp
index 0cd7d0417b..632d2b11cb 100644
--- a/layout/base/nsDisplayList.cpp
+++ b/layout/base/nsDisplayList.cpp
@@ -542,8 +542,7 @@ nsDisplayListBuilder::AddAnimationsAndTransitionsToLayer(Layer* aLayer,
     // EffectCompositor needs to know that we refused to run this animation
     // asynchronously so that it will not throttle the main thread
     // animation.
-    aFrame->Properties().Set(nsIFrame::RefusedAsyncAnimationProperty(),
-                            reinterpret_cast<void*>(intptr_t(true)));
+    aFrame->Properties().Set(nsIFrame::RefusedAsyncAnimationProperty(), true);
 
     // We need to schedule another refresh driver run so that EffectCompositor
     // gets a chance to unthrottle the animation.
@@ -2255,11 +2254,11 @@ nsDisplayBackgroundImage::GetDestAreaInternal(nsDisplayListBuilder* aBuilder)
   nsPresContext* presContext = mFrame->PresContext();
   uint32_t flags = aBuilder->GetBackgroundPaintFlags();
   nsRect borderArea = nsRect(ToReferenceFrame(), mFrame->GetSize());
-  const nsStyleBackground::Layer &layer = mBackgroundStyle->mLayers[mLayer];
+  const nsStyleImageLayers::Layer& layer = mBackgroundStyle->mLayers.mLayers[mLayer];
 
   nsBackgroundLayerState state =
-    nsCSSRendering::PrepareBackgroundLayer(presContext, mFrame, flags,
-                                           borderArea, borderArea, layer);
+    nsCSSRendering::PrepareImageLayer(presContext, mFrame, flags,
+                                      borderArea, borderArea, layer);
   return state.mDestArea;
 }
 
@@ -2296,13 +2295,13 @@ static nsStyleContext* GetBackgroundStyleContext(nsIFrame* aFrame)
 /* static */ void
 SetBackgroundClipRegion(DisplayListClipState::AutoSaveRestore& aClipState,
                         nsIFrame* aFrame, const nsPoint& aToReferenceFrame,
-                        const nsStyleBackground::Layer& aLayer,
+                        const nsStyleImageLayers::Layer& aLayer,
                         bool aWillPaintBorder)
 {
   nsRect borderBox = nsRect(aToReferenceFrame, aFrame->GetSize());
 
-  nsCSSRendering::BackgroundClipState clip;
-  nsCSSRendering::GetBackgroundClip(aLayer, aFrame, *aFrame->StyleBorder(),
+  nsCSSRendering::ImageLayerClipState clip;
+  nsCSSRendering::GetImageLayerClip(aLayer, aFrame, *aFrame->StyleBorder(),
                                     borderBox, borderBox, aWillPaintBorder,
                                     aFrame->PresContext()->AppUnitsPerDevPixel(),
                                     &clip);
@@ -2402,18 +2401,18 @@ nsDisplayBackgroundImage::AppendBackgroundItemsToTop(nsDisplayListBuilder* aBuil
 
   // Passing bg == nullptr in this macro will result in one iteration with
   // i = 0.
-  NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT(i, bg) {
-    if (bg->mLayers[i].mImage.IsEmpty()) {
+  NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, bg->mLayers) {
+    if (bg->mLayers.mLayers[i].mImage.IsEmpty()) {
       continue;
     }
 
-    if (bg->mLayers[i].mBlendMode != NS_STYLE_BLEND_NORMAL) {
+    if (bg->mLayers.mLayers[i].mBlendMode != NS_STYLE_BLEND_NORMAL) {
       needBlendContainer = true;
     }
 
     DisplayListClipState::AutoSaveRestore clipState(aBuilder);
     if (!aBuilder->IsForEventDelivery()) {
-      const nsStyleBackground::Layer& layer = bg->mLayers[i];
+      const nsStyleImageLayers::Layer& layer = bg->mLayers.mLayers[i];
       SetBackgroundClipRegion(clipState, aFrame, toRef,
                               layer, willPaintBorder);
     }
@@ -2477,19 +2476,19 @@ nsDisplayBackgroundImage::IsSingleFixedPositionImage(nsDisplayListBuilder* aBuil
   if (!mBackgroundStyle)
     return false;
 
-  if (mBackgroundStyle->mLayers.Length() != 1)
+  if (mBackgroundStyle->mLayers.mLayers.Length() != 1)
     return false;
 
   nsPresContext* presContext = mFrame->PresContext();
   uint32_t flags = aBuilder->GetBackgroundPaintFlags();
   nsRect borderArea = nsRect(ToReferenceFrame(), mFrame->GetSize());
-  const nsStyleBackground::Layer &layer = mBackgroundStyle->mLayers[mLayer];
+  const nsStyleImageLayers::Layer &layer = mBackgroundStyle->mLayers.mLayers[mLayer];
 
-  if (layer.mAttachment != NS_STYLE_BG_ATTACHMENT_FIXED)
+  if (layer.mAttachment != NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED)
     return false;
 
   nsBackgroundLayerState state =
-    nsCSSRendering::PrepareBackgroundLayer(presContext, mFrame, flags,
+    nsCSSRendering::PrepareImageLayer(presContext, mFrame, flags,
                                            borderArea, aClipRect, layer);
   nsImageRenderer* imageRenderer = &state.mImageRenderer;
   // We only care about images here, not gradients.
@@ -2505,8 +2504,8 @@ nsDisplayBackgroundImage::IsSingleFixedPositionImage(nsDisplayListBuilder* aBuil
 bool
 nsDisplayBackgroundImage::IsNonEmptyFixedImage() const
 {
-  return mBackgroundStyle->mLayers[mLayer].mAttachment == NS_STYLE_BG_ATTACHMENT_FIXED &&
-         !mBackgroundStyle->mLayers[mLayer].mImage.IsEmpty();
+  return mBackgroundStyle->mLayers.mLayers[mLayer].mAttachment == NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED &&
+         !mBackgroundStyle->mLayers.mLayers[mLayer].mImage.IsEmpty();
 }
 
 bool
@@ -2535,10 +2534,10 @@ nsDisplayBackgroundImage::CanOptimizeToImageLayer(LayerManager* aManager,
   nsPresContext* presContext = mFrame->PresContext();
   uint32_t flags = aBuilder->GetBackgroundPaintFlags();
   nsRect borderArea = nsRect(ToReferenceFrame(), mFrame->GetSize());
-  const nsStyleBackground::Layer &layer = mBackgroundStyle->mLayers[mLayer];
+  const nsStyleImageLayers::Layer &layer = mBackgroundStyle->mLayers.mLayers[mLayer];
 
   nsBackgroundLayerState state =
-    nsCSSRendering::PrepareBackgroundLayer(presContext, mFrame, flags,
+    nsCSSRendering::PrepareImageLayer(presContext, mFrame, flags,
                                            borderArea, borderArea, layer);
   nsImageRenderer* imageRenderer = &state.mImageRenderer;
   // We only care about images here, not gradients.
@@ -2559,8 +2558,8 @@ nsDisplayBackgroundImage::CanOptimizeToImageLayer(LayerManager* aManager,
   // For 'contain' and 'cover', we allow any pixel of the image to be sampled
   // because there isn't going to be any spriting/atlasing going on.
   bool allowPartialImages =
-    (layer.mSize.mWidthType == nsStyleBackground::Size::eContain ||
-     layer.mSize.mWidthType == nsStyleBackground::Size::eCover);
+    (layer.mSize.mWidthType == nsStyleImageLayers::Size::eContain ||
+     layer.mSize.mWidthType == nsStyleImageLayers::Size::eCover);
   if (!allowPartialImages && !state.mFillArea.Contains(state.mDestArea)) {
     return false;
   }
@@ -2614,7 +2613,7 @@ nsDisplayBackgroundImage::ShouldCreateOwnLayer(nsDisplayListBuilder* aBuilder,
   }
 
   if (nsLayoutUtils::AnimatedImageLayersEnabled() && mBackgroundStyle) {
-    const nsStyleBackground::Layer &layer = mBackgroundStyle->mLayers[mLayer];
+    const nsStyleImageLayers::Layer &layer = mBackgroundStyle->mLayers.mLayers[mLayer];
     const nsStyleImage* image = &layer.mImage;
     if (image->GetType() == eStyleImageType_Image) {
       imgIRequest* imgreq = image->GetImageData();
@@ -2773,13 +2772,13 @@ nsDisplayBackgroundImage::GetInsideClipRegion(nsDisplayItem* aItem,
     clipRect = canvasFrame->CanvasArea() + aItem->ToReferenceFrame();
   } else {
     switch (aClip) {
-    case NS_STYLE_BG_CLIP_BORDER:
+    case NS_STYLE_IMAGELAYER_CLIP_BORDER:
       clipRect = nsRect(aItem->ToReferenceFrame(), frame->GetSize());
       break;
-    case NS_STYLE_BG_CLIP_PADDING:
+    case NS_STYLE_IMAGELAYER_CLIP_PADDING:
       clipRect = frame->GetPaddingRect() - frame->GetPosition() + aItem->ToReferenceFrame();
       break;
-    case NS_STYLE_BG_CLIP_CONTENT:
+    case NS_STYLE_IMAGELAYER_CLIP_CONTENT:
       clipRect = frame->GetContentRectRelativeToSelf() + aItem->ToReferenceFrame();
       break;
     default:
@@ -2810,10 +2809,10 @@ nsDisplayBackgroundImage::GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
   if (mFrame->StyleBorder()->mBoxDecorationBreak ==
         NS_STYLE_BOX_DECORATION_BREAK_CLONE ||
       (!mFrame->GetPrevContinuation() && !mFrame->GetNextContinuation())) {
-    const nsStyleBackground::Layer& layer = mBackgroundStyle->mLayers[mLayer];
+    const nsStyleImageLayers::Layer& layer = mBackgroundStyle->mLayers.mLayers[mLayer];
     if (layer.mImage.IsOpaque() && layer.mBlendMode == NS_STYLE_BLEND_NORMAL &&
-        layer.mRepeat.mXRepeat != NS_STYLE_BG_REPEAT_SPACE &&
-        layer.mRepeat.mYRepeat != NS_STYLE_BG_REPEAT_SPACE) {
+        layer.mRepeat.mXRepeat != NS_STYLE_IMAGELAYER_REPEAT_SPACE &&
+        layer.mRepeat.mYRepeat != NS_STYLE_IMAGELAYER_REPEAT_SPACE) {
       result = GetInsideClipRegion(this, layer.mClip, mBounds);
     }
   }
@@ -2837,10 +2836,10 @@ nsDisplayBackgroundImage::GetPositioningArea()
     return nsRect();
   }
   nsIFrame* attachedToFrame;
-  return nsCSSRendering::ComputeBackgroundPositioningArea(
+  return nsCSSRendering::ComputeImageLayerPositioningArea(
       mFrame->PresContext(), mFrame,
       nsRect(ToReferenceFrame(), mFrame->GetSize()),
-      mBackgroundStyle->mLayers[mLayer],
+      mBackgroundStyle->mLayers.mLayers[mLayer],
       &attachedToFrame) + ToReferenceFrame();
 }
 
@@ -2857,7 +2856,7 @@ nsDisplayBackgroundImage::RenderingMightDependOnPositioningAreaSizeChange()
     return true;
   }
 
-  const nsStyleBackground::Layer &layer = mBackgroundStyle->mLayers[mLayer];
+  const nsStyleImageLayers::Layer &layer = mBackgroundStyle->mLayers.mLayers[mLayer];
   if (layer.RenderingMightDependOnPositioningAreaSizeChange()) {
     return true;
   }
@@ -2933,7 +2932,7 @@ void nsDisplayBackgroundImage::ComputeInvalidationRegion(nsDisplayListBuilder* a
     return;
   }
   if (aBuilder->ShouldSyncDecodeImages()) {
-    const nsStyleImage& image = mBackgroundStyle->mLayers[mLayer].mImage;
+    const nsStyleImage& image = mBackgroundStyle->mLayers.mLayers[mLayer].mImage;
     if (image.GetType() == eStyleImageType_Image &&
         geometry->ShouldInvalidateToSyncDecodeImages()) {
       aInvalidRegion->Or(*aInvalidRegion, bounds);
@@ -2979,7 +2978,7 @@ nsDisplayBackgroundImage::GetBoundsInternal(nsDisplayListBuilder* aBuilder) {
       clipRect = rootRect + aBuilder->ToReferenceFrame(mFrame);
     }
   }
-  const nsStyleBackground::Layer& layer = mBackgroundStyle->mLayers[mLayer];
+  const nsStyleImageLayers::Layer& layer = mBackgroundStyle->mLayers.mLayers[mLayer];
   return nsCSSRendering::GetBackgroundLayerRect(presContext, mFrame,
                                                 borderBox, clipRect, layer,
                                                 aBuilder->GetBackgroundPaintFlags());
@@ -3227,7 +3226,7 @@ nsDisplayBackgroundColor::GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
 
   *aSnap = true;
 
-  const nsStyleBackground::Layer& bottomLayer = mBackgroundStyle->BottomLayer();
+  const nsStyleImageLayers::Layer& bottomLayer = mBackgroundStyle->BottomLayer();
   nsRect borderBox = nsRect(ToReferenceFrame(), mFrame->GetSize());
   return nsDisplayBackgroundImage::GetInsideClipRegion(this, bottomLayer.mClip,
                                                        borderBox);
diff --git a/layout/base/nsDisplayList.h b/layout/base/nsDisplayList.h
index f03720bd11..62c2228b32 100644
--- a/layout/base/nsDisplayList.h
+++ b/layout/base/nsDisplayList.h
@@ -204,7 +204,6 @@ class nsDisplayListBuilder {
   };
 
 public:
-  typedef mozilla::FramePropertyDescriptor FramePropertyDescriptor;
   typedef mozilla::FrameLayerBuilder FrameLayerBuilder;
   typedef mozilla::DisplayItemClip DisplayItemClip;
   typedef mozilla::DisplayListClipState DisplayListClipState;
@@ -960,8 +959,8 @@ public:
     nsRect mDirtyRect;
   };
 
-  NS_DECLARE_FRAME_PROPERTY(OutOfFlowDisplayDataProperty,
-                            DeleteValue<OutOfFlowDisplayData>)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(OutOfFlowDisplayDataProperty,
+                                      OutOfFlowDisplayData)
 
   static OutOfFlowDisplayData* GetOutOfFlowData(nsIFrame* aFrame)
   {
@@ -969,7 +968,7 @@ public:
       aFrame->Properties().Get(OutOfFlowDisplayDataProperty()));
   }
 
-  NS_DECLARE_FRAME_PROPERTY(Preserve3DDirtyRectProperty, DeleteValue<nsRect>)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(Preserve3DDirtyRectProperty, nsRect)
 
   nsPresContext* CurrentPresContext() {
     return CurrentPresShellState()->mPresShell->GetPresContext();
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index 501c07b8e1..4c0e25c981 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -806,6 +806,15 @@ nsLayoutUtils::AsyncPanZoomEnabled(nsIFrame* aFrame)
   return widget->AsyncPanZoomEnabled();
 }
 
+float
+nsLayoutUtils::GetCurrentAPZResolutionScale(nsIPresShell* aShell) {
+#if !defined(MOZ_WIDGET_ANDROID) || defined(MOZ_ANDROID_APZ)
+  return aShell ? aShell->GetCumulativeNonRootScaleResolution() : 1.0;
+#else
+  return 1.0f;
+#endif
+}
+
 // Return the maximum displayport size, based on the LayerManager's maximum
 // supported texture size. The result is in app units.
 static nscoord
@@ -1862,19 +1871,18 @@ nsLayoutUtils::IsFixedPosFrameInDisplayPort(const nsIFrame* aFrame)
   return ViewportHasDisplayPort(aFrame->PresContext());
 }
 
-NS_DECLARE_FRAME_PROPERTY(ScrollbarThumbLayerized, nullptr)
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(ScrollbarThumbLayerized, bool)
 
 /* static */ void
 nsLayoutUtils::SetScrollbarThumbLayerization(nsIFrame* aThumbFrame, bool aLayerize)
 {
-  aThumbFrame->Properties().Set(ScrollbarThumbLayerized(),
-    reinterpret_cast<void*>(intptr_t(aLayerize)));
+  aThumbFrame->Properties().Set(ScrollbarThumbLayerized(), aLayerize);
 }
 
 bool
 nsLayoutUtils::IsScrollbarThumbLayerized(nsIFrame* aThumbFrame)
 {
-  return reinterpret_cast<intptr_t>(aThumbFrame->Properties().Get(ScrollbarThumbLayerized()));
+  return aThumbFrame->Properties().Get(ScrollbarThumbLayerized());
 }
 
 // static
@@ -2057,7 +2065,7 @@ nsLayoutUtils::GetEventCoordinatesRelativeTo(nsIWidget* aWidget,
       nsPoint pt(presContext->DevPixelsToAppUnits(aPoint.x),
                  presContext->DevPixelsToAppUnits(aPoint.y));
       pt = pt - view->ViewToWidgetOffset();
-      pt = pt.RemoveResolution(presContext->PresShell()->GetCumulativeNonRootScaleResolution());
+      pt = pt.RemoveResolution(GetCurrentAPZResolutionScale(presContext->PresShell()));
       return pt;
     }
   }
@@ -2096,7 +2104,7 @@ nsLayoutUtils::GetEventCoordinatesRelativeTo(nsIWidget* aWidget,
   nsIPresShell* shell = aFrame->PresContext()->PresShell();
 
   // XXX Bug 1224748 - Update nsLayoutUtils functions to correctly handle nsPresShell resolution
-  widgetToView = widgetToView.RemoveResolution(shell->GetCumulativeNonRootScaleResolution());
+  widgetToView = widgetToView.RemoveResolution(GetCurrentAPZResolutionScale(shell));
 
   /* If we encountered a transform, we can't do simple arithmetic to figure
    * out how to convert back to aFrame's coordinates and must use the CTM.
@@ -2849,7 +2857,7 @@ nsLayoutUtils::TranslateViewToWidget(nsPresContext* aPresContext,
   }
 
   nsPoint pt = (aPt +
-  viewOffset).ApplyResolution(aPresContext->PresShell()->GetCumulativeNonRootScaleResolution());
+  viewOffset).ApplyResolution(GetCurrentAPZResolutionScale(aPresContext->PresShell()));
   LayoutDeviceIntPoint relativeToViewWidget(aPresContext->AppUnitsToDevPixels(pt.x),
                                             aPresContext->AppUnitsToDevPixels(pt.y));
   return relativeToViewWidget + WidgetToWidgetOffset(viewWidget, aWidget);
@@ -3918,7 +3926,7 @@ ComputeConcreteObjectSize(const nsSize& aConstraintSize,
 
 // (Helper for HasInitialObjectFitAndPosition, to check
 // each "object-position" coord.)
-typedef nsStyleBackground::Position::PositionCoord PositionCoord;
+typedef nsStyleImageLayers::Position::PositionCoord PositionCoord;
 static bool
 IsCoord50Pct(const PositionCoord& aCoord)
 {
@@ -3932,7 +3940,7 @@ IsCoord50Pct(const PositionCoord& aCoord)
 static bool
 HasInitialObjectFitAndPosition(const nsStylePosition* aStylePos)
 {
-  const nsStyleBackground::Position& objectPos = aStylePos->mObjectPosition;
+  const nsStyleImageLayers::Position& objectPos = aStylePos->mObjectPosition;
 
   return aStylePos->mObjectFit == NS_STYLE_OBJECT_FIT_FILL &&
     IsCoord50Pct(objectPos.mXPosition) &&
@@ -5123,7 +5131,7 @@ nsLayoutUtils::ComputeSizeWithIntrinsicDimensions(WritingMode aWM,
     FrameProperties props = aFrame->Properties();
     bool didImposeMainSize;
     nscoord imposedMainSize =
-      reinterpret_cast<nscoord>(props.Get(nsIFrame::FlexItemMainSizeOverride(), &didImposeMainSize));
+      props.Get(nsIFrame::FlexItemMainSizeOverride(), &didImposeMainSize);
     if (didImposeMainSize) {
       imposedMainSizeStyleCoord.emplace(imposedMainSize,
                                         nsStyleCoord::CoordConstructor);
@@ -6813,7 +6821,7 @@ nsLayoutUtils::GetFrameTransparency(nsIFrame* aBackgroundFrame,
   const nsStyleBackground* bg = bgSC->StyleBackground();
   if (NS_GET_A(bg->mBackgroundColor) < 255 ||
       // bottom layer's clip is used for the color
-      bg->BottomLayer().mClip != NS_STYLE_BG_CLIP_BORDER)
+      bg->BottomLayer().mClip != NS_STYLE_IMAGELAYER_CLIP_BORDER)
     return eTransparencyTransparent;
   return eTransparencyOpaque;
 }
@@ -8956,6 +8964,18 @@ nsLayoutUtils::IsScrollFrameWithSnapping(nsIFrame* aFrame)
          styles.mScrollSnapTypeX != NS_STYLE_SCROLL_SNAP_TYPE_NONE;
 }
 
+/* static */ nsBlockFrame*
+nsLayoutUtils::GetFloatContainingBlock(nsIFrame* aFrame)
+{
+  nsIFrame* ancestor = aFrame->GetParent();
+  while (ancestor && !ancestor->IsFloatContainingBlock()) {
+    ancestor = ancestor->GetParent();
+  }
+  MOZ_ASSERT(!ancestor || GetAsBlock(ancestor),
+             "Float containing block can only be block frame");
+  return static_cast<nsBlockFrame*>(ancestor);
+}
+
 // The implementation of this calculation is adapted from
 // Element::GetBoundingClientRect().
 /* static */ CSSRect
diff --git a/layout/base/nsLayoutUtils.h b/layout/base/nsLayoutUtils.h
index 7e79e6ea42..fb236243f8 100644
--- a/layout/base/nsLayoutUtils.h
+++ b/layout/base/nsLayoutUtils.h
@@ -2669,6 +2669,12 @@ public:
    */
   static bool AsyncPanZoomEnabled(nsIFrame* aFrame);
 
+  /**
+   * Returns the current APZ Resolution Scale. When Java Pan/Zoom is
+   * enabled in Fennec it will always return 1.0.
+   */
+  static float GetCurrentAPZResolutionScale(nsIPresShell* aShell);
+
   /**
    * Log a key/value pair for APZ testing during a paint.
    * @param aManager   The data will be written to the APZTestData associated
@@ -2839,6 +2845,11 @@ public:
   static CSSRect GetBoundingContentRect(const nsIContent* aContent,
                                         const nsIScrollableFrame* aRootScrollFrame);
 
+  /**
+   * Returns the first ancestor who is a float containing block.
+   */
+  static nsBlockFrame* GetFloatContainingBlock(nsIFrame* aFrame);
+
 private:
   static uint32_t sFontSizeInflationEmPerLine;
   static uint32_t sFontSizeInflationMinTwips;
diff --git a/layout/forms/nsTextControlFrame.cpp b/layout/forms/nsTextControlFrame.cpp
index 4fc4aff404..36e8e66e7a 100644
--- a/layout/forms/nsTextControlFrame.cpp
+++ b/layout/forms/nsTextControlFrame.cpp
@@ -1238,8 +1238,7 @@ nsTextControlFrame::SetInitialChildList(ChildListID     aListID,
     NS_ASSERTION(txtCtrl, "Content not a text control element");
     txtCtrl->InitializeKeyboardEventListeners();
 
-    nsPoint* contentScrollPos = static_cast<nsPoint*>
-      (Properties().Get(ContentScrollPos()));
+    nsPoint* contentScrollPos = Properties().Get(ContentScrollPos());
     if (contentScrollPos) {
       // If we have a scroll pos stored to be passed to our anonymous
       // div, do it here!
diff --git a/layout/forms/nsTextControlFrame.h b/layout/forms/nsTextControlFrame.h
index 3b1430c905..0157d3b4a7 100644
--- a/layout/forms/nsTextControlFrame.h
+++ b/layout/forms/nsTextControlFrame.h
@@ -32,7 +32,7 @@ class nsTextControlFrame final : public nsContainerFrame,
 public:
   NS_DECL_FRAMEARENA_HELPERS
 
-  NS_DECLARE_FRAME_PROPERTY(ContentScrollPos, DeleteValue<nsPoint>)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(ContentScrollPos, nsPoint)
 
   explicit nsTextControlFrame(nsStyleContext* aContext);
   virtual ~nsTextControlFrame();
@@ -152,10 +152,6 @@ public:
 
   NS_DECL_QUERYFRAME
 
-  // Temp reference to scriptrunner
-  // We could make these auto-Revoking via the "delete" entry for safety
-  NS_DECLARE_FRAME_PROPERTY(TextControlInitializer, nullptr)
-
 protected:
   /**
    * Launch the reflow on the child frames - see nsTextControlFrame::Reflow()
@@ -202,6 +198,11 @@ protected:
   friend class EditorInitializer;
   friend class nsTextEditorState; // needs access to UpdateValueDisplay
 
+  // Temp reference to scriptrunner
+  // We could make these auto-Revoking via the "delete" entry for safety
+  NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(TextControlInitializer,
+                                         EditorInitializer)
+
   class EditorInitializer : public nsRunnable {
   public:
     explicit EditorInitializer(nsTextControlFrame* aFrame) :
diff --git a/layout/generic/RubyUtils.cpp b/layout/generic/RubyUtils.cpp
index adef88227a..f340663bc2 100644
--- a/layout/generic/RubyUtils.cpp
+++ b/layout/generic/RubyUtils.cpp
@@ -13,22 +13,13 @@
 
 using namespace mozilla;
 
-NS_DECLARE_FRAME_PROPERTY(ReservedISize, nullptr);
-
-union NSCoordValue
-{
-  nscoord mCoord;
-  void* mPointer;
-  static_assert(sizeof(nscoord) <= sizeof(void*),
-                "Cannot store nscoord in pointer");
-};
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(ReservedISize, nscoord)
 
 /* static */ void
 RubyUtils::SetReservedISize(nsIFrame* aFrame, nscoord aISize)
 {
   MOZ_ASSERT(IsExpandableRubyBox(aFrame));
-  NSCoordValue value = { aISize };
-  aFrame->Properties().Set(ReservedISize(), value.mPointer);
+  aFrame->Properties().Set(ReservedISize(), aISize);
 }
 
 /* static */ void
@@ -42,9 +33,7 @@ RubyUtils::ClearReservedISize(nsIFrame* aFrame)
 RubyUtils::GetReservedISize(nsIFrame* aFrame)
 {
   MOZ_ASSERT(IsExpandableRubyBox(aFrame));
-  NSCoordValue value;
-  value.mPointer = aFrame->Properties().Get(ReservedISize());
-  return value.mCoord;
+  return aFrame->Properties().Get(ReservedISize());
 }
 
 AutoRubyTextContainerArray::AutoRubyTextContainerArray(
@@ -57,6 +46,36 @@ AutoRubyTextContainerArray::AutoRubyTextContainerArray(
   }
 }
 
+nsIFrame*
+RubyColumn::Iterator::operator*() const
+{
+  nsIFrame* frame;
+  if (mIndex == -1) {
+    frame = mColumn.mBaseFrame;
+  } else {
+    frame = mColumn.mTextFrames[mIndex];
+  }
+  MOZ_ASSERT(frame, "Frame here cannot be null");
+  return frame;
+}
+
+void
+RubyColumn::Iterator::SkipUntilExistingFrame()
+{
+  if (mIndex == -1) {
+    if (mColumn.mBaseFrame) {
+      return;
+    }
+    ++mIndex;
+  }
+  int32_t numTextFrames = mColumn.mTextFrames.Length();
+  for (; mIndex < numTextFrames; ++mIndex) {
+    if (mColumn.mTextFrames[mIndex]) {
+      break;
+    }
+  }
+}
+
 RubySegmentEnumerator::RubySegmentEnumerator(nsRubyFrame* aRubyFrame)
 {
   nsIFrame* frame = aRubyFrame->PrincipalChildList().FirstChild();
diff --git a/layout/generic/RubyUtils.h b/layout/generic/RubyUtils.h
index 886acf7958..1497c93c40 100644
--- a/layout/generic/RubyUtils.h
+++ b/layout/generic/RubyUtils.h
@@ -133,7 +133,55 @@ struct MOZ_STACK_CLASS RubyColumn
   nsRubyBaseFrame* mBaseFrame;
   nsAutoTArray<nsRubyTextFrame*, RTC_ARRAY_SIZE> mTextFrames;
   bool mIsIntraLevelWhitespace;
+
   RubyColumn() : mBaseFrame(nullptr), mIsIntraLevelWhitespace(false) { }
+
+  // Helper class to support iteration across the frames within a single
+  // RubyColumn (the column's ruby base and its annotations).
+  class MOZ_STACK_CLASS Iterator
+  {
+  public:
+    nsIFrame* operator*() const;
+
+    Iterator& operator++() { ++mIndex; SkipUntilExistingFrame(); return *this; }
+    Iterator operator++(int) { auto ret = *this; ++*this; return ret; }
+
+    friend bool operator==(const Iterator& aIter1, const Iterator& aIter2)
+    {
+      MOZ_ASSERT(&aIter1.mColumn == &aIter2.mColumn,
+                 "Should only compare iterators of the same ruby column");
+      return aIter1.mIndex == aIter2.mIndex;
+    }
+    friend bool operator!=(const Iterator& aIter1, const Iterator& aIter2)
+    {
+      return !(aIter1 == aIter2);
+    }
+
+  private:
+    Iterator(const RubyColumn& aColumn, int32_t aIndex)
+      : mColumn(aColumn)
+      , mIndex(aIndex)
+    {
+      MOZ_ASSERT(aIndex == -1 ||
+                 (aIndex >= 0 &&
+                  aIndex <= int32_t(aColumn.mTextFrames.Length())));
+      SkipUntilExistingFrame();
+    }
+    friend struct RubyColumn; // for the constructor
+
+    void SkipUntilExistingFrame();
+
+    const RubyColumn& mColumn;
+    // -1 means the ruby base frame,
+    // non-negative means the index of ruby text frame
+    // a value of mTextFrames.Length() means we're done iterating
+    int32_t mIndex = -1;
+  };
+
+  Iterator begin() const { return Iterator(*this, -1); }
+  Iterator end() const { return Iterator(*this, mTextFrames.Length()); }
+  Iterator cbegin() const { return begin(); }
+  Iterator cend() const { return end(); }
 };
 
 /**
diff --git a/layout/generic/StickyScrollContainer.cpp b/layout/generic/StickyScrollContainer.cpp
index 285656b4d2..00fdbaf828 100644
--- a/layout/generic/StickyScrollContainer.cpp
+++ b/layout/generic/StickyScrollContainer.cpp
@@ -17,8 +17,8 @@
 
 namespace mozilla {
 
-NS_DECLARE_FRAME_PROPERTY(StickyScrollContainerProperty,
-                          DeleteValue<StickyScrollContainer>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(StickyScrollContainerProperty,
+                                    StickyScrollContainer)
 
 StickyScrollContainer::StickyScrollContainer(nsIScrollableFrame* aScrollFrame)
   : mScrollFrame(aScrollFrame)
diff --git a/layout/generic/crashtests/1229437-1.html b/layout/generic/crashtests/1229437-1.html
new file mode 100644
index 0000000000..2f1e66c31e
--- /dev/null
+++ b/layout/generic/crashtests/1229437-1.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<meta charset="UTF-8">
+<style>
+  rbc { display: ruby-base-container; }
+</style>
+<div style="-moz-column-width: 1px">
+  <ruby><rbc></rbc><rb><div style="float: right"></div></rb></ruby>X
+</div>
diff --git a/layout/generic/crashtests/1229437-2.html b/layout/generic/crashtests/1229437-2.html
new file mode 100644
index 0000000000..5b6ce63294
--- /dev/null
+++ b/layout/generic/crashtests/1229437-2.html
@@ -0,0 +1,5 @@
+<!DOCTYPE html>
+<meta charset="UTF-8">
+<div style="-moz-column-width: 1px">
+  <ruby><rb></rb><rb><div style="float: right"></div></rb></ruby>X
+</div>
diff --git a/layout/generic/crashtests/crashtests.list b/layout/generic/crashtests/crashtests.list
index 19ec9f66a3..3444555093 100644
--- a/layout/generic/crashtests/crashtests.list
+++ b/layout/generic/crashtests/crashtests.list
@@ -599,6 +599,8 @@ load 1223568-1.html
 load 1223568-2.html
 pref(layout.css.grid.enabled,true) load 1225118.html
 pref(layout.css.grid.enabled,true) load 1225376.html
+load 1229437-1.html
+load 1229437-2.html
 load details-display-none-summary-1.html
 load details-display-none-summary-2.html
 load details-display-none-summary-3.html
diff --git a/layout/generic/nsBlockFrame.cpp b/layout/generic/nsBlockFrame.cpp
index 0d8eb96c9a..6edd2980e3 100644
--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -285,19 +285,13 @@ RecordReflowStatus(bool aChildIsBlock, nsReflowStatus aFrameReflowStatus)
 }
 #endif
 
-// Destructor function for the overflowLines frame property
-static void
-DestroyOverflowLines(void* aPropertyValue)
-{
-  NS_ERROR("Overflow lines should never be destroyed by the FramePropertyTable");
-}
-
-NS_DECLARE_FRAME_PROPERTY(OverflowLinesProperty, DestroyOverflowLines)
+NS_DECLARE_FRAME_PROPERTY_WITH_DTOR_NEVER_CALLED(OverflowLinesProperty,
+                                                 nsBlockFrame::FrameLines)
 NS_DECLARE_FRAME_PROPERTY_FRAMELIST(OverflowOutOfFlowsProperty)
 NS_DECLARE_FRAME_PROPERTY_FRAMELIST(PushedFloatProperty)
 NS_DECLARE_FRAME_PROPERTY_FRAMELIST(OutsideBulletProperty)
-NS_DECLARE_FRAME_PROPERTY(InsideBulletProperty, nullptr)
-NS_DECLARE_FRAME_PROPERTY(BlockEndEdgeOfChildrenProperty, nullptr)
+NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(InsideBulletProperty, nsBulletFrame)
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(BlockEndEdgeOfChildrenProperty, nscoord)
 
 //----------------------------------------------------------------------
 
@@ -1636,8 +1630,7 @@ nsBlockFrame::ComputeFinalSize(const nsHTMLReflowState& aReflowState,
 
   FrameProperties properties = Properties();
   if (blockEndEdgeOfChildren != finalSize.BSize(wm) - borderPadding.BEnd(wm)) {
-    properties.Set(BlockEndEdgeOfChildrenProperty(),
-                   NS_INT32_TO_PTR(blockEndEdgeOfChildren));
+    properties.Set(BlockEndEdgeOfChildrenProperty(), blockEndEdgeOfChildren);
   } else {
     properties.Delete(BlockEndEdgeOfChildrenProperty());
   }
@@ -1771,8 +1764,8 @@ nsBlockFrame::UpdateOverflow()
                                     kPrincipalList | kFloatList);
 
   bool found;
-  nscoord blockEndEdgeOfChildren = NS_PTR_TO_INT32(
-    Properties().Get(BlockEndEdgeOfChildrenProperty(), &found));
+  nscoord blockEndEdgeOfChildren =
+    Properties().Get(BlockEndEdgeOfChildrenProperty(), &found);
   if (found) {
     ConsiderBlockEndEdgeOfChildren(GetWritingMode(),
                                    blockEndEdgeOfChildren, overflowAreas);
@@ -4906,8 +4899,7 @@ nsBlockFrame::GetOverflowLines() const
   if (!HasOverflowLines()) {
     return nullptr;
   }
-  FrameLines* prop =
-    static_cast<FrameLines*>(Properties().Get(OverflowLinesProperty()));
+  FrameLines* prop = Properties().Get(OverflowLinesProperty());
   NS_ASSERTION(prop && !prop->mLines.empty() &&
                prop->mLines.front()->GetChildCount() == 0 ? prop->mFrames.IsEmpty() :
                  prop->mLines.front()->mFirstChild == prop->mFrames.FirstChild(),
@@ -4921,8 +4913,7 @@ nsBlockFrame::RemoveOverflowLines()
   if (!HasOverflowLines()) {
     return nullptr;
   }
-  FrameLines* prop =
-    static_cast<FrameLines*>(Properties().Remove(OverflowLinesProperty()));
+  FrameLines* prop = Properties().Remove(OverflowLinesProperty());
   NS_ASSERTION(prop && !prop->mLines.empty() &&
                prop->mLines.front()->GetChildCount() == 0 ? prop->mFrames.IsEmpty() :
                  prop->mLines.front()->mFirstChild == prop->mFrames.FirstChild(),
@@ -4935,8 +4926,7 @@ void
 nsBlockFrame::DestroyOverflowLines()
 {
   NS_ASSERTION(HasOverflowLines(), "huh?");
-  FrameLines* prop =
-    static_cast<FrameLines*>(Properties().Remove(OverflowLinesProperty()));
+  FrameLines* prop = Properties().Remove(OverflowLinesProperty());
   NS_ASSERTION(prop && prop->mLines.empty(),
                "value should always be stored but empty when destroying");
   RemoveStateBits(NS_BLOCK_HAS_OVERFLOW_LINES);
@@ -5012,8 +5002,7 @@ nsBlockFrame::GetInsideBullet() const
     return nullptr;
   }
   NS_ASSERTION(!HasOutsideBullet(), "invalid bullet state");
-  nsBulletFrame* frame =
-    static_cast<nsBulletFrame*>(Properties().Get(InsideBulletProperty()));
+  nsBulletFrame* frame = Properties().Get(InsideBulletProperty());
   NS_ASSERTION(frame && frame->GetType() == nsGkAtoms::bulletFrame,
                "bogus inside bullet frame");
   return frame;
@@ -6716,8 +6705,7 @@ nsLineBox* nsBlockFrame::GetFirstLineContaining(nscoord y)
 
   FrameProperties props = Properties();
   
-  nsLineBox* property = static_cast<nsLineBox*>
-    (props.Get(LineCursorProperty()));
+  nsLineBox* property = props.Get(LineCursorProperty());
   line_iterator cursor = mLines.begin(property);
   nsRect cursorArea = cursor->GetVisualOverflowArea();
 
diff --git a/layout/generic/nsBlockFrame.h b/layout/generic/nsBlockFrame.h
index cfb939fd54..00ccd8111e 100644
--- a/layout/generic/nsBlockFrame.h
+++ b/layout/generic/nsBlockFrame.h
@@ -371,10 +371,10 @@ protected:
   }
 #endif
 
-  NS_DECLARE_FRAME_PROPERTY(LineCursorProperty, nullptr)
+  NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(LineCursorProperty, nsLineBox)
   nsLineBox* GetLineCursor() {
     return (GetStateBits() & NS_BLOCK_HAS_LINE_CURSOR) ?
-      static_cast<nsLineBox*>(Properties().Get(LineCursorProperty())) : nullptr;
+      Properties().Get(LineCursorProperty()) : nullptr;
   }
 
   nsLineBox* NewLineBox(nsIFrame* aFrame, bool aIsBlock) {
diff --git a/layout/generic/nsBulletFrame.cpp b/layout/generic/nsBulletFrame.cpp
index 6aa1f5f29f..cb402b20f5 100644
--- a/layout/generic/nsBulletFrame.cpp
+++ b/layout/generic/nsBulletFrame.cpp
@@ -41,7 +41,7 @@ using namespace mozilla;
 using namespace mozilla::gfx;
 using namespace mozilla::image;
 
-NS_DECLARE_FRAME_PROPERTY(FontSizeInflationProperty, nullptr)
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(FontSizeInflationProperty, float)
 
 NS_IMPL_FRAMEARENA_HELPERS(nsBulletFrame)
 
@@ -849,22 +849,13 @@ nsBulletFrame::GetLoadGroup(nsPresContext *aPresContext, nsILoadGroup **aLoadGro
   *aLoadGroup = doc->GetDocumentLoadGroup().take();
 }
 
-union VoidPtrOrFloat {
-  VoidPtrOrFloat() : p(nullptr) {}
-
-  void *p;
-  float f;
-};
-
 float
 nsBulletFrame::GetFontSizeInflation() const
 {
   if (!HasFontSizeInflation()) {
     return 1.0f;
   }
-  VoidPtrOrFloat u;
-  u.p = Properties().Get(FontSizeInflationProperty());
-  return u.f;
+  return Properties().Get(FontSizeInflationProperty());
 }
 
 void
@@ -879,9 +870,7 @@ nsBulletFrame::SetFontSizeInflation(float aInflation)
   }
 
   AddStateBits(BULLET_FRAME_HAS_FONT_INFLATION);
-  VoidPtrOrFloat u;
-  u.f = aInflation;
-  Properties().Set(FontSizeInflationProperty(), u.p);
+  Properties().Set(FontSizeInflationProperty(), aInflation);
 }
 
 already_AddRefed<imgIContainer>
diff --git a/layout/generic/nsCanvasFrame.cpp b/layout/generic/nsCanvasFrame.cpp
index ba93759e1e..68af05950e 100644
--- a/layout/generic/nsCanvasFrame.cpp
+++ b/layout/generic/nsCanvasFrame.cpp
@@ -402,11 +402,12 @@ nsCanvasFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
     bool needBlendContainer = false;
 
     // Create separate items for each background layer.
-    NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT(i, bg) {
-      if (bg->mLayers[i].mImage.IsEmpty()) {
+    const nsStyleImageLayers& layers = bg->mLayers;
+    NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, layers) {
+      if (layers.mLayers[i].mImage.IsEmpty()) {
         continue;
       }
-      if (bg->mLayers[i].mBlendMode != NS_STYLE_BLEND_NORMAL) {
+      if (layers.mLayers[i].mBlendMode != NS_STYLE_BLEND_NORMAL) {
         needBlendContainer = true;
       }
       nsDisplayCanvasBackgroundImage* bgItem =
diff --git a/layout/generic/nsCanvasFrame.h b/layout/generic/nsCanvasFrame.h
index 062a8394bf..6a9ed28337 100644
--- a/layout/generic/nsCanvasFrame.h
+++ b/layout/generic/nsCanvasFrame.h
@@ -220,8 +220,8 @@ public:
     // compositing layer. Since we know their background painting area can't
     // change (unless the viewport size itself changes), async scrolling
     // will work well.
-    return mBackgroundStyle->mLayers[mLayer].mAttachment == NS_STYLE_BG_ATTACHMENT_FIXED &&
-           !mBackgroundStyle->mLayers[mLayer].mImage.IsEmpty();
+    return mBackgroundStyle->mLayers.mLayers[mLayer].mAttachment == NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED &&
+           !mBackgroundStyle->mLayers.mLayers[mLayer].mImage.IsEmpty();
   }
  
   // We still need to paint a background color as well as an image for this item, 
diff --git a/layout/generic/nsContainerFrame.cpp b/layout/generic/nsContainerFrame.cpp
index 0a131e5d0a..d60f91e63f 100644
--- a/layout/generic/nsContainerFrame.cpp
+++ b/layout/generic/nsContainerFrame.cpp
@@ -188,13 +188,12 @@ void
 nsContainerFrame::SafelyDestroyFrameListProp(nsIFrame* aDestructRoot,
                                              nsIPresShell* aPresShell,
                                              FramePropertyTable* aPropTable,
-                                             const FramePropertyDescriptor* aProp)
+                                             FrameListPropertyDescriptor aProp)
 {
   // Note that the last frame can be removed through another route and thus
   // delete the property -- that's why we fetch the property again before
   // removing each frame rather than fetching it once and iterating the list.
-  while (nsFrameList* frameList =
-           static_cast<nsFrameList*>(aPropTable->Get(this, aProp))) {
+  while (nsFrameList* frameList = aPropTable->Get(this, aProp)) {
     nsIFrame* frame = frameList->RemoveFirstChild();
     if (MOZ_LIKELY(frame)) {
       frame->DestroyFrom(aDestructRoot);
@@ -275,15 +274,14 @@ nsContainerFrame::GetChildList(ChildListID aListID) const
   }
 }
 
-static void AppendIfNonempty(const nsIFrame* aFrame,
-                            FramePropertyTable* aPropTable,
-                            const FramePropertyDescriptor* aProperty,
-                            nsTArray<nsIFrame::ChildList>* aLists,
-                            nsIFrame::ChildListID aListID)
+static void
+AppendIfNonempty(const nsIFrame* aFrame,
+                 FramePropertyTable* aPropTable,
+                 nsContainerFrame::FrameListPropertyDescriptor aProperty,
+                 nsTArray<nsIFrame::ChildList>* aLists,
+                 nsIFrame::ChildListID aListID)
 {
-  nsFrameList* list = static_cast<nsFrameList*>(
-    aPropTable->Get(aFrame, aProperty));
-  if (list) {
+  if (nsFrameList* list = aPropTable->Get(aFrame, aProperty)) {
     list->AppendIfNonempty(aLists, aListID);
   }
 }
@@ -1376,9 +1374,10 @@ nsContainerFrame::DisplayOverflowContainers(nsDisplayListBuilder*   aBuilder,
 
 static bool
 TryRemoveFrame(nsIFrame* aFrame, FramePropertyTable* aPropTable,
-               const FramePropertyDescriptor* aProp, nsIFrame* aChildToRemove)
+               nsContainerFrame::FrameListPropertyDescriptor aProp,
+               nsIFrame* aChildToRemove)
 {
-  nsFrameList* list = static_cast<nsFrameList*>(aPropTable->Get(aFrame, aProp));
+  nsFrameList* list = aPropTable->Get(aFrame, aProp);
   if (list && list->StartRemoveFrame(aChildToRemove)) {
     // aChildToRemove *may* have been removed from this list.
     if (list->IsEmpty()) {
@@ -1399,11 +1398,9 @@ nsContainerFrame::StealFrame(nsIFrame* aChild,
     nsFrameList* list = GetOverflowFrames();
     if (!list || !list->ContainsFrame(aChild)) {
       FramePropertyTable* propTable = PresContext()->PropertyTable();
-      list = static_cast<nsFrameList*>(
-               propTable->Get(this, OverflowContainersProperty()));
+      list = propTable->Get(this, OverflowContainersProperty());
       if (!list || !list->ContainsFrame(aChild)) {
-        list = static_cast<nsFrameList*>(
-                 propTable->Get(this, ExcessOverflowContainersProperty()));
+        list = propTable->Get(this, ExcessOverflowContainersProperty());
         MOZ_ASSERT(list && list->ContainsFrame(aChild), "aChild isn't our child"
                    " or on a frame list not supported by StealFrame");
       }
@@ -1572,22 +1569,21 @@ nsContainerFrame::SetOverflowFrames(const nsFrameList& aOverflowFrames)
 }
 
 nsFrameList*
-nsContainerFrame::GetPropTableFrames(const FramePropertyDescriptor* aProperty) const
+nsContainerFrame::GetPropTableFrames(
+  FrameListPropertyDescriptor aProperty) const
 {
-  FramePropertyTable* propTable = PresContext()->PropertyTable();
-  return static_cast<nsFrameList*>(propTable->Get(this, aProperty));
+  return PresContext()->PropertyTable()->Get(this, aProperty);
 }
 
 nsFrameList*
-nsContainerFrame::RemovePropTableFrames(const FramePropertyDescriptor* aProperty)
+nsContainerFrame::RemovePropTableFrames(FrameListPropertyDescriptor aProperty)
 {
-  FramePropertyTable* propTable = PresContext()->PropertyTable();
-  return static_cast<nsFrameList*>(propTable->Remove(this, aProperty));
+  return PresContext()->PropertyTable()->Remove(this, aProperty);
 }
 
 void
-nsContainerFrame::SetPropTableFrames(nsFrameList*                   aFrameList,
-                                     const FramePropertyDescriptor* aProperty)
+nsContainerFrame::SetPropTableFrames(nsFrameList* aFrameList,
+                                     FrameListPropertyDescriptor aProperty)
 {
   NS_PRECONDITION(aProperty && aFrameList, "null ptr");
   NS_PRECONDITION(
@@ -1997,8 +1993,8 @@ nsOverflowContinuationTracker::EndFinish(nsIFrame* aChild)
   // Forget mOverflowContList if it was deleted.
   nsPresContext* pc = aChild->PresContext();
   FramePropertyTable* propTable = pc->PropertyTable();
-  nsFrameList* eoc = static_cast<nsFrameList*>(propTable->Get(mParent,
-                       nsContainerFrame::ExcessOverflowContainersProperty()));
+  nsFrameList* eoc = propTable->Get(
+    mParent, nsContainerFrame::ExcessOverflowContainersProperty());
   if (eoc != mOverflowContList) {
     nsFrameList* oc = static_cast<nsFrameList*>(propTable->Get(mParent,
                         nsContainerFrame::OverflowContainersProperty()));
diff --git a/layout/generic/nsContainerFrame.h b/layout/generic/nsContainerFrame.h
index f5c85ae41e..b27a2545d5 100644
--- a/layout/generic/nsContainerFrame.h
+++ b/layout/generic/nsContainerFrame.h
@@ -431,15 +431,6 @@ public:
                                 const nsRect&           aDirtyRect,
                                 const nsDisplayListSet& aLists) override;
 
-  /**
-   * Destructor function for the proptable-stored framelists --
-   * it should never be called.
-   */
-  static void DestroyFrameList(void* aPropertyValue)
-  {
-    MOZ_ASSERT(false, "The owning frame should destroy its nsFrameList props");
-  }
-
   static void PlaceFrameView(nsIFrame* aFrame)
   {
     if (aFrame->HasView())
@@ -448,8 +439,10 @@ public:
       nsContainerFrame::PositionChildViews(aFrame);
   }
 
-#define NS_DECLARE_FRAME_PROPERTY_FRAMELIST(prop)                     \
-  NS_DECLARE_FRAME_PROPERTY(prop, nsContainerFrame::DestroyFrameList)
+#define NS_DECLARE_FRAME_PROPERTY_FRAMELIST(prop) \
+  NS_DECLARE_FRAME_PROPERTY_WITH_DTOR_NEVER_CALLED(prop, nsFrameList)
+
+  typedef PropertyDescriptor<nsFrameList> FrameListPropertyDescriptor;
 
   NS_DECLARE_FRAME_PROPERTY_FRAMELIST(OverflowProperty)
   NS_DECLARE_FRAME_PROPERTY_FRAMELIST(OverflowContainersProperty)
@@ -458,9 +451,9 @@ public:
 
 #ifdef DEBUG
   // Use this to suppress the CRAZY_SIZE assertions.
-  NS_DECLARE_FRAME_PROPERTY(DebugReflowingWithInfiniteISize, nullptr)
+  NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(DebugReflowingWithInfiniteISize, bool)
   bool IsCrazySizeAssertSuppressed() const {
-    return Properties().Get(DebugReflowingWithInfiniteISize()) != nullptr;
+    return Properties().Get(DebugReflowingWithInfiniteISize());
   }
 #endif
 
@@ -601,20 +594,20 @@ protected:
    * Get the PresContext-stored nsFrameList named aPropID for this frame.
    * May return null.
    */
-  nsFrameList* GetPropTableFrames(const FramePropertyDescriptor* aProperty) const;
+  nsFrameList* GetPropTableFrames(FrameListPropertyDescriptor aProperty) const;
 
   /**
    * Remove and return the PresContext-stored nsFrameList named aPropID for
    * this frame. May return null.
    */
-  nsFrameList* RemovePropTableFrames(const FramePropertyDescriptor* aProperty);
+  nsFrameList* RemovePropTableFrames(FrameListPropertyDescriptor aProperty);
 
   /**
    * Set the PresContext-stored nsFrameList named aPropID for this frame
    * to the given aFrameList, which must not be null.
    */
-  void SetPropTableFrames(nsFrameList*                   aFrameList,
-                          const FramePropertyDescriptor* aProperty);
+  void SetPropTableFrames(nsFrameList* aFrameList,
+                          FrameListPropertyDescriptor aProperty);
 
   /**
    * Safely destroy the frames on the nsFrameList stored on aProp for this
@@ -624,7 +617,7 @@ protected:
   void SafelyDestroyFrameListProp(nsIFrame* aDestructRoot,
                                   nsIPresShell* aPresShell,
                                   mozilla::FramePropertyTable* aPropTable,
-                                  const FramePropertyDescriptor* aProp);
+                                  FrameListPropertyDescriptor aProp);
 
   // ==========================================================================
 
@@ -805,8 +798,7 @@ inline
 nsFrameList*
 nsContainerFrame::GetOverflowFrames() const
 {
-  nsFrameList* list =
-    static_cast<nsFrameList*>(Properties().Get(OverflowProperty()));
+  nsFrameList* list = Properties().Get(OverflowProperty());
   NS_ASSERTION(!list || !list->IsEmpty(), "Unexpected empty overflow list");
   return list;
 }
@@ -815,8 +807,7 @@ inline
 nsFrameList*
 nsContainerFrame::StealOverflowFrames()
 {
-  nsFrameList* list =
-    static_cast<nsFrameList*>(Properties().Remove(OverflowProperty()));
+  nsFrameList* list = Properties().Remove(OverflowProperty());
   NS_ASSERTION(!list || !list->IsEmpty(), "Unexpected empty overflow list");
   return list;
 }
diff --git a/layout/generic/nsFlexContainerFrame.cpp b/layout/generic/nsFlexContainerFrame.cpp
index c8b082148f..32fe69039f 100644
--- a/layout/generic/nsFlexContainerFrame.cpp
+++ b/layout/generic/nsFlexContainerFrame.cpp
@@ -3781,7 +3781,7 @@ public:
     NS_ASSERTION(aItem.HasIntrinsicRatio(),
                  "This should only be needed for items with an aspect ratio");
 
-    mItemProps.Set(nsIFrame::FlexItemMainSizeOverride(), reinterpret_cast<void *>(aItem.GetMainSize()));
+    mItemProps.Set(nsIFrame::FlexItemMainSizeOverride(), aItem.GetMainSize());
   }
 
   ~AutoFlexItemMainSizeOverride() {
diff --git a/layout/generic/nsFloatManager.cpp b/layout/generic/nsFloatManager.cpp
index f15f1dfd88..e101d27b13 100644
--- a/layout/generic/nsFloatManager.cpp
+++ b/layout/generic/nsFloatManager.cpp
@@ -323,7 +323,7 @@ nsFloatManager::CalculateRegionFor(WritingMode          aWM,
   return region;
 }
 
-NS_DECLARE_FRAME_PROPERTY(FloatRegionProperty, DeleteValue<nsMargin>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(FloatRegionProperty, nsMargin)
 
 LogicalRect
 nsFloatManager::GetRegionFor(WritingMode aWM, nsIFrame* aFloat,
diff --git a/layout/generic/nsFontInflationData.cpp b/layout/generic/nsFontInflationData.cpp
index 5654485571..42d6877194 100644
--- a/layout/generic/nsFontInflationData.cpp
+++ b/layout/generic/nsFontInflationData.cpp
@@ -16,8 +16,8 @@
 using namespace mozilla;
 using namespace mozilla::layout;
 
-NS_DECLARE_FRAME_PROPERTY(FontInflationDataProperty,
-                          DeleteValue<nsFontInflationData>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(FontInflationDataProperty,
+                                    nsFontInflationData)
 
 /* static */ nsFontInflationData*
 nsFontInflationData::FindFontInflationDataFor(const nsIFrame *aFrame)
diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index eca8e9159f..aa7547e8be 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -160,7 +160,7 @@ static void RefreshContentFrames(nsPresContext* aPresContext, nsIContent * aStar
 
 #include "prenv.h"
 
-NS_DECLARE_FRAME_PROPERTY(BoxMetricsProperty, DeleteValue<nsBoxLayoutMetrics>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(BoxMetricsProperty, nsBoxLayoutMetrics)
 
 static void
 InitBoxMetrics(nsIFrame* aFrame, bool aClear)
@@ -240,8 +240,8 @@ nsFrame::SetVerifyStyleTreeEnable(bool aEnabled)
 
 #endif
 
-NS_DECLARE_FRAME_PROPERTY(AbsoluteContainingBlockProperty,
-                          DeleteValue<nsAbsoluteContainingBlock>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(AbsoluteContainingBlockProperty,
+                                    nsAbsoluteContainingBlock)
 
 bool
 nsIFrame::HasAbsolutelyPositionedChildren() const {
@@ -251,8 +251,7 @@ nsIFrame::HasAbsolutelyPositionedChildren() const {
 nsAbsoluteContainingBlock*
 nsIFrame::GetAbsoluteContainingBlock() const {
   NS_ASSERTION(IsAbsoluteContainer(), "The frame is not marked as an abspos container correctly");
-  nsAbsoluteContainingBlock* absCB = static_cast<nsAbsoluteContainingBlock*>
-    (Properties().Get(AbsoluteContainingBlockProperty()));
+  nsAbsoluteContainingBlock* absCB = Properties().Get(AbsoluteContainingBlockProperty());
   NS_ASSERTION(absCB, "The frame is marked as an abspos container but doesn't have the property");
   return absCB;
 }
@@ -781,33 +780,35 @@ nsFrame::DidSetStyleContext(nsStyleContext* aOldStyleContext)
                                    aOldStyleContext->StyleBackground() :
                                    nullptr;
   const nsStyleBackground *newBG = StyleBackground();
+  const nsStyleImageLayers& oldBGLayers = oldBG->mLayers;
+  const nsStyleImageLayers& newBGLayers = newBG->mLayers;
   if (oldBG) {
-    NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT(i, oldBG) {
+    NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, oldBGLayers) {
       // If there is an image in oldBG that's not in newBG, drop it.
-      if (i >= newBG->mImageCount ||
-          !oldBG->mLayers[i].mImage.ImageDataEquals(newBG->mLayers[i].mImage)) {
-        const nsStyleImage& oldImage = oldBG->mLayers[i].mImage;
+      if (i >= newBGLayers.mImageCount ||
+          !oldBGLayers.mLayers[i].mImage.ImageDataEquals(newBGLayers.mLayers[i].mImage)) {
+        const nsStyleImage& oldImage = oldBGLayers.mLayers[i].mImage;
         if (oldImage.GetType() != eStyleImageType_Image) {
           continue;
         }
 
         imageLoader->DisassociateRequestFromFrame(oldImage.GetImageData(),
                                                   this);
-      }          
+      }
     }
   }
 
-  NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT(i, newBG) {
+  NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, newBGLayers) {
     // If there is an image in newBG that's not in oldBG, add it.
-    if (!oldBG || i >= oldBG->mImageCount ||
-        !newBG->mLayers[i].mImage.ImageDataEquals(oldBG->mLayers[i].mImage)) {
-      const nsStyleImage& newImage = newBG->mLayers[i].mImage;
+    if (!oldBG || i >= oldBGLayers.mImageCount ||
+        !newBGLayers.mLayers[i].mImage.ImageDataEquals(oldBGLayers.mLayers[i].mImage)) {
+      const nsStyleImage& newImage = newBGLayers.mLayers[i].mImage;
       if (newImage.GetType() != eStyleImageType_Image) {
         continue;
       }
 
       imageLoader->AssociateRequestToFrame(newImage.GetImageData(), this);
-    }          
+    }
   }
 
   if (aOldStyleContext) {
@@ -4811,7 +4812,7 @@ nsIFrame* nsIFrame::GetTailContinuation()
   return frame;
 }
 
-NS_DECLARE_FRAME_PROPERTY(ViewProperty, nullptr)
+NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(ViewProperty, nsView)
 
 // Associated view object
 nsView*
@@ -4822,9 +4823,9 @@ nsIFrame::GetView() const
     return nullptr;
 
   // Check for a property on the frame
-  void* value = Properties().Get(ViewProperty());
+  nsView* value = Properties().Get(ViewProperty());
   NS_ASSERTION(value, "frame state bit was set but frame has no view");
-  return static_cast<nsView*>(value);
+  return value;
 }
 
 /* virtual */ nsView*
@@ -6255,9 +6256,8 @@ nsFrame::GetPointFromOffset(int32_t inOffset, nsPoint* outPoint)
       // If the embedding level isn't set, just use the CSS direction
       // property.
       bool hasEmbeddingLevel;
-      nsBidiLevel embeddingLevel =
-        NS_PTR_TO_INT32(Properties().Get(nsBidi::EmbeddingLevelProperty(),
-                                         &hasEmbeddingLevel));
+      nsBidiLevel embeddingLevel = Properties().Get(
+        nsBidi::EmbeddingLevelProperty(), &hasEmbeddingLevel);
       bool isRTL = hasEmbeddingLevel
         ? IS_LEVEL_RTL(embeddingLevel)
         : StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
@@ -7387,7 +7387,7 @@ nsFrame::AccessibleType()
 }
 #endif
 
-NS_DECLARE_FRAME_PROPERTY(OverflowAreasProperty, DeleteValue<nsOverflowAreas>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(OverflowAreasProperty, nsOverflowAreas)
 
 bool
 nsIFrame::ClearOverflowRects()
@@ -7711,7 +7711,7 @@ nsIFrame::FinishAndStoreOverflow(nsOverflowAreas& aOverflowAreas,
       Properties().Delete(nsIFrame::InitialOverflowProperty());
     }
 #ifdef DEBUG
-    Properties().Set(nsIFrame::DebugInitialOverflowPropertyApplied(), nullptr);
+    Properties().Set(nsIFrame::DebugInitialOverflowPropertyApplied(), true);
 #endif
   } else {
 #ifdef DEBUG
@@ -9063,16 +9063,13 @@ nsIFrame::IsSelected() const
 }
 
 /*static*/ void
-nsIFrame::DestroyContentArray(void* aPropertyValue)
+nsIFrame::DestroyContentArray(ContentArray* aArray)
 {
-  typedef nsTArray<nsIContent*> T;
-  T* arr = static_cast<T*>(aPropertyValue);
-  for (T::size_type i = 0; i < arr->Length(); ++i) {
-    nsIContent* content = (*arr)[i];
+  for (nsIContent* content : *aArray) {
     content->UnbindFromTree();
     NS_RELEASE(content);
   }
-  delete arr;
+  delete aArray;
 }
 
 bool
diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
index f519b0eae7..20d0747bb5 100644
--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -5728,7 +5728,7 @@ ScrollSnapHelper(SnappingEdgeCallback& aCallback, nsIFrame* aFrame,
         nsPoint offset = f->GetOffsetTo(aScrolledFrame);
         nsRect edgesRect = nsRect(offset, frameRect.Size());
         for (size_t coordNum = 0; coordNum < coordCount; coordNum++) {
-          const nsStyleBackground::Position &coordPosition =
+          const nsStyleImageLayers::Position &coordPosition =
             f->StyleDisplay()->mScrollSnapCoordinate[coordNum];
           nsPoint coordPoint = edgesRect.TopLeft() - aScrollSnapDestination;
           coordPoint += nsPoint(coordPosition.mXPosition.mLength,
diff --git a/layout/generic/nsGridContainerFrame.cpp b/layout/generic/nsGridContainerFrame.cpp
index a1116bc333..0ac5e89d8d 100644
--- a/layout/generic/nsGridContainerFrame.cpp
+++ b/layout/generic/nsGridContainerFrame.cpp
@@ -2320,8 +2320,8 @@ ContentContribution(nsIFrame*                         aChild,
     }
 #ifdef DEBUG
     // This will suppress various CRAZY_SIZE warnings for this reflow.
-    parent->Properties().Set(nsContainerFrame::DebugReflowingWithInfiniteISize(),
-                             parent /* anything non-null will do */);
+    parent->Properties().Set(
+      nsContainerFrame::DebugReflowingWithInfiniteISize(), true);
 #endif
     // XXX this will give mostly correct results for now (until bug 1174569).
     LogicalSize availableSize(wm, INFINITE_ISIZE_COORD, NS_UNCONSTRAINEDSIZE);
diff --git a/layout/generic/nsGridContainerFrame.h b/layout/generic/nsGridContainerFrame.h
index cd43dc7e53..a914cbf9af 100644
--- a/layout/generic/nsGridContainerFrame.h
+++ b/layout/generic/nsGridContainerFrame.h
@@ -105,18 +105,18 @@ public:
     StateBits mState;
   };
 
-  NS_DECLARE_FRAME_PROPERTY(GridItemContainingBlockRect, DeleteValue<nsRect>)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(GridItemContainingBlockRect, nsRect)
 
-  NS_DECLARE_FRAME_PROPERTY(GridColTrackInfo, DeleteValue<ComputedGridTrackInfo>)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(GridColTrackInfo, ComputedGridTrackInfo)
   const ComputedGridTrackInfo* GetComputedTemplateColumns()
   {
-    return static_cast<ComputedGridTrackInfo*>(Properties().Get(GridColTrackInfo()));
+    return Properties().Get(GridColTrackInfo());
   }
 
-  NS_DECLARE_FRAME_PROPERTY(GridRowTrackInfo, DeleteValue<ComputedGridTrackInfo>)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(GridRowTrackInfo, ComputedGridTrackInfo)
   const ComputedGridTrackInfo* GetComputedTemplateRows()
   {
-    return static_cast<ComputedGridTrackInfo*>(Properties().Get(GridRowTrackInfo()));
+    return Properties().Get(GridRowTrackInfo());
   }
 
 protected:
@@ -597,13 +597,13 @@ protected:
    * grid-template-columns / grid-template-rows are stored in this frame
    * property when needed, as a ImplicitNamedAreas* value.
    */
-  NS_DECLARE_FRAME_PROPERTY(ImplicitNamedAreasProperty,
-                            DeleteValue<ImplicitNamedAreas>)
+  typedef nsTHashtable<nsStringHashKey> ImplicitNamedAreas;
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(ImplicitNamedAreasProperty,
+                                      ImplicitNamedAreas)
   void InitImplicitNamedAreas(const nsStylePosition* aStyle);
   void AddImplicitNamedAreas(const nsTArray<nsTArray<nsString>>& aLineNameLists);
-  typedef nsTHashtable<nsStringHashKey> ImplicitNamedAreas;
   ImplicitNamedAreas* GetImplicitNamedAreas() const {
-    return static_cast<ImplicitNamedAreas*>(Properties().Get(ImplicitNamedAreasProperty()));
+    return Properties().Get(ImplicitNamedAreasProperty());
   }
   bool HasImplicitNamedArea(const nsString& aName) const {
     ImplicitNamedAreas* areas = GetImplicitNamedAreas();
diff --git a/layout/generic/nsHTMLReflowState.cpp b/layout/generic/nsHTMLReflowState.cpp
index eb6b29cbac..765d936e94 100644
--- a/layout/generic/nsHTMLReflowState.cpp
+++ b/layout/generic/nsHTMLReflowState.cpp
@@ -2388,12 +2388,12 @@ nsHTMLReflowState::InitConstraints(nsPresContext*     aPresContext,
 
 static void
 UpdateProp(FrameProperties& aProps,
-           const FramePropertyDescriptor* aProperty,
+           const FramePropertyDescriptor<nsMargin>* aProperty,
            bool aNeeded,
            nsMargin& aNewValue)
 {
   if (aNeeded) {
-    nsMargin* propValue = static_cast<nsMargin*>(aProps.Get(aProperty));
+    nsMargin* propValue = aProps.Get(aProperty);
     if (propValue) {
       *propValue = aNewValue;
     } else {
diff --git a/layout/generic/nsIFrame.h b/layout/generic/nsIFrame.h
index 0da6ef763f..3a0d168b0a 100644
--- a/layout/generic/nsIFrame.h
+++ b/layout/generic/nsIFrame.h
@@ -377,16 +377,16 @@ struct IntrinsicSize {
 
 /// Generic destructor for frame properties. Calls delete.
 template<typename T>
-static void DeleteValue(void* aPropertyValue)
+static void DeleteValue(T* aPropertyValue)
 {
-  delete static_cast<T*>(aPropertyValue);
+  delete aPropertyValue;
 }
 
 /// Generic destructor for frame properties. Calls Release().
 template<typename T>
-static void ReleaseValue(void* aPropertyValue)
+static void ReleaseValue(T* aPropertyValue)
 {
-  static_cast<T*>(aPropertyValue)->Release();
+  aPropertyValue->Release();
 }
 
 //----------------------------------------------------------------------
@@ -415,7 +415,9 @@ static void ReleaseValue(void* aPropertyValue)
 class nsIFrame : public nsQueryFrame
 {
 public:
-  typedef mozilla::FramePropertyDescriptor FramePropertyDescriptor;
+  template<typename T=void>
+  using PropertyDescriptor = const mozilla::FramePropertyDescriptor<T>*;
+
   typedef mozilla::FrameProperties FrameProperties;
   typedef mozilla::layers::Layer Layer;
   typedef mozilla::layout::FrameChildList ChildList;
@@ -842,68 +844,93 @@ public:
   
   nsPoint GetPositionIgnoringScrolling();
 
-  static void DestroyContentArray(void* aPropertyValue);
+  typedef nsAutoTArray<nsIContent*, 2> ContentArray;
+  static void DestroyContentArray(ContentArray* aArray);
 
-#define NS_DECLARE_FRAME_PROPERTY(prop, dtor)                            \
-  static const FramePropertyDescriptor* prop() {                         \
-    static const FramePropertyDescriptor descriptor = { dtor, nullptr }; \
-    return &descriptor;                                                  \
+#define NS_DECLARE_FRAME_PROPERTY_WITH_DTOR(prop, type, dtor)             \
+  static const mozilla::FramePropertyDescriptor<type>* prop() {           \
+    static MOZ_CONSTEXPR auto descriptor =                                \
+      mozilla::FramePropertyDescriptor<type>::NewWithDestructor<dtor>();  \
+    return &descriptor;                                                   \
   }
+
 // Don't use this unless you really know what you're doing!
-#define NS_DECLARE_FRAME_PROPERTY_WITH_FRAME_IN_DTOR(prop, dtor)         \
-  static const FramePropertyDescriptor* prop() {                         \
-    static const FramePropertyDescriptor descriptor = { nullptr, dtor }; \
-    return &descriptor;                                                  \
+#define NS_DECLARE_FRAME_PROPERTY_WITH_FRAME_IN_DTOR(prop, type, dtor)    \
+  static const mozilla::FramePropertyDescriptor<type>* prop() {           \
+    static MOZ_CONSTEXPR auto descriptor = mozilla::                      \
+      FramePropertyDescriptor<type>::NewWithDestructorWithFrame<dtor>();  \
+    return &descriptor;                                                   \
   }
 
-  NS_DECLARE_FRAME_PROPERTY(IBSplitSibling, nullptr)
-  NS_DECLARE_FRAME_PROPERTY(IBSplitPrevSibling, nullptr)
+#define NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(prop, type)                \
+  static const mozilla::FramePropertyDescriptor<type>* prop() {           \
+    static MOZ_CONSTEXPR auto descriptor =                                \
+      mozilla::FramePropertyDescriptor<type>::NewWithoutDestructor();     \
+    return &descriptor;                                                   \
+  }
 
-  NS_DECLARE_FRAME_PROPERTY(NormalPositionProperty, DeleteValue<nsPoint>)
-  NS_DECLARE_FRAME_PROPERTY(ComputedOffsetProperty, DeleteValue<nsMargin>)
+#define NS_DECLARE_FRAME_PROPERTY_DELETABLE(prop, type) \
+  NS_DECLARE_FRAME_PROPERTY_WITH_DTOR(prop, type, DeleteValue)
 
-  NS_DECLARE_FRAME_PROPERTY(OutlineInnerRectProperty, DeleteValue<nsRect>)
-  NS_DECLARE_FRAME_PROPERTY(PreEffectsBBoxProperty, DeleteValue<nsRect>)
-  NS_DECLARE_FRAME_PROPERTY(PreTransformOverflowAreasProperty,
-                            DeleteValue<nsOverflowAreas>)
+#define NS_DECLARE_FRAME_PROPERTY_RELEASABLE(prop, type) \
+  NS_DECLARE_FRAME_PROPERTY_WITH_DTOR(prop, type, ReleaseValue)
+
+#define NS_DECLARE_FRAME_PROPERTY_WITH_DTOR_NEVER_CALLED(prop, type)  \
+  static void AssertOnDestroyingProperty##prop(type*) {               \
+    MOZ_ASSERT_UNREACHABLE("Frame property " #prop " should never "   \
+                           "be destroyed by the FramePropertyTable"); \
+  }                                                                   \
+  NS_DECLARE_FRAME_PROPERTY_WITH_DTOR(prop, type,                     \
+                                      AssertOnDestroyingProperty##prop)
+
+#define NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(prop, type) \
+  NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(prop, mozilla::SmallValueHolder<type>)
+
+  NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(IBSplitSibling, nsIFrame)
+  NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(IBSplitPrevSibling, nsIFrame)
+
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(NormalPositionProperty, nsPoint)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(ComputedOffsetProperty, nsMargin)
+
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(OutlineInnerRectProperty, nsRect)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(PreEffectsBBoxProperty, nsRect)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(PreTransformOverflowAreasProperty,
+                                      nsOverflowAreas)
 
   // The initial overflow area passed to FinishAndStoreOverflow. This is only set
   // on frames that Preserve3D() or HasPerspective() or IsTransformed(), and
   // when at least one of the overflow areas differs from the frame bound rect.
-  NS_DECLARE_FRAME_PROPERTY(InitialOverflowProperty,
-                            DeleteValue<nsOverflowAreas>)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(InitialOverflowProperty, nsOverflowAreas)
 
 #ifdef DEBUG
   // InitialOverflowPropertyDebug is added to the frame to indicate that either
   // the InitialOverflowProperty has been stored or the InitialOverflowProperty
   // has been suppressed due to being set to the default value (frame bounds)
-  NS_DECLARE_FRAME_PROPERTY(DebugInitialOverflowPropertyApplied, nullptr)
+  NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(DebugInitialOverflowPropertyApplied, bool)
 #endif
 
-  NS_DECLARE_FRAME_PROPERTY(UsedMarginProperty, DeleteValue<nsMargin>)
-  NS_DECLARE_FRAME_PROPERTY(UsedPaddingProperty, DeleteValue<nsMargin>)
-  NS_DECLARE_FRAME_PROPERTY(UsedBorderProperty, DeleteValue<nsMargin>)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(UsedMarginProperty, nsMargin)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(UsedPaddingProperty, nsMargin)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(UsedBorderProperty, nsMargin)
 
-  NS_DECLARE_FRAME_PROPERTY(LineBaselineOffset, nullptr)
+  NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(LineBaselineOffset, nscoord)
 
   // Temporary override for a flex item's main-size property (either width
   // or height), imposed by its flex container.
-  // XXX: We don't have bug 1064843, so use the previous declaration system
-  // (see bug 1030952 part 3 and TenFourFox issue 493).
-  NS_DECLARE_FRAME_PROPERTY(FlexItemMainSizeOverride, nullptr)
+  NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(FlexItemMainSizeOverride, nscoord)
 
-  NS_DECLARE_FRAME_PROPERTY(CachedBackgroundImage, ReleaseValue<gfxASurface>)
-  NS_DECLARE_FRAME_PROPERTY(CachedBackgroundImageDT, ReleaseValue<DrawTarget>)
+  NS_DECLARE_FRAME_PROPERTY_RELEASABLE(CachedBackgroundImage, gfxASurface)
+  NS_DECLARE_FRAME_PROPERTY_RELEASABLE(CachedBackgroundImageDT, DrawTarget)
 
-  NS_DECLARE_FRAME_PROPERTY(InvalidationRect, DeleteValue<nsRect>)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(InvalidationRect, nsRect)
 
-  NS_DECLARE_FRAME_PROPERTY(RefusedAsyncAnimationProperty, nullptr)
+  NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(RefusedAsyncAnimationProperty, bool)
 
-  NS_DECLARE_FRAME_PROPERTY(GenConProperty, DestroyContentArray)
+  NS_DECLARE_FRAME_PROPERTY_WITH_DTOR(GenConProperty, ContentArray,
+                                      DestroyContentArray)
 
   nsTArray<nsIContent*>* GetGenConPseudos() {
-    const FramePropertyDescriptor* prop = GenConProperty();
-    return static_cast<nsTArray<nsIContent*>*>(Properties().Get(prop));
+    return Properties().Get(GenConProperty());
   }
 
   /**
@@ -1193,8 +1220,7 @@ public:
 
   bool RefusedAsyncAnimation() const
   {
-    void* prop = Properties().Get(nsIFrame::RefusedAsyncAnimationProperty());
-    return bool(reinterpret_cast<intptr_t>(prop));
+    return Properties().Get(RefusedAsyncAnimationProperty());
   }
 
   /**
@@ -3090,8 +3116,7 @@ private:
 
   void MarkAbsoluteFramesForDisplayList(nsDisplayListBuilder* aBuilder, const nsRect& aDirtyRect);
 
-  static void DestroyPaintedPresShellList(void* propertyValue) {
-    nsTArray<nsWeakPtr>* list = static_cast<nsTArray<nsWeakPtr>*>(propertyValue);
+  static void DestroyPaintedPresShellList(nsTArray<nsWeakPtr>* list) {
     list->Clear();
     delete list;
   }
@@ -3099,7 +3124,9 @@ private:
   // Stores weak references to all the PresShells that were painted during
   // the last paint event so that we can increment their paint count during
   // empty transactions
-  NS_DECLARE_FRAME_PROPERTY(PaintedPresShellsProperty, DestroyPaintedPresShellList)
+  NS_DECLARE_FRAME_PROPERTY_WITH_DTOR(PaintedPresShellsProperty,
+                                      nsTArray<nsWeakPtr>,
+                                      DestroyPaintedPresShellList)
   
   nsTArray<nsWeakPtr>* PaintedPresShellList() {
     nsTArray<nsWeakPtr>* list = static_cast<nsTArray<nsWeakPtr>*>(
diff --git a/layout/generic/nsInlineFrame.cpp b/layout/generic/nsInlineFrame.cpp
index f4e9cb2a75..e5925bd3aa 100644
--- a/layout/generic/nsInlineFrame.cpp
+++ b/layout/generic/nsInlineFrame.cpp
@@ -316,20 +316,13 @@ nsInlineFrame::ReparentFloatsForInlineChild(nsIFrame* aOurLineContainer,
     return;
   }
 
-  nsIFrame* ancestor = aFrame;
-  do {
-    ancestor = ancestor->GetParent();
-    if (!ancestor)
-      return;
-  } while (!ancestor->IsFloatContainingBlock());
-
-  if (ancestor == aOurLineContainer)
+  nsBlockFrame* frameBlock = nsLayoutUtils::GetFloatContainingBlock(aFrame);
+  if (!frameBlock || frameBlock == aOurLineContainer) {
     return;
+  }
 
   nsBlockFrame* ourBlock = nsLayoutUtils::GetAsBlock(aOurLineContainer);
   NS_ASSERTION(ourBlock, "Not a block, but broke vertically?");
-  nsBlockFrame* frameBlock = nsLayoutUtils::GetAsBlock(ancestor);
-  NS_ASSERTION(frameBlock, "ancestor not a block");
 
   while (true) {
     ourBlock->ReparentFloats(aFrame, frameBlock, false);
diff --git a/layout/generic/nsRubyBaseContainerFrame.cpp b/layout/generic/nsRubyBaseContainerFrame.cpp
index 8cfb71dde0..364324babe 100644
--- a/layout/generic/nsRubyBaseContainerFrame.cpp
+++ b/layout/generic/nsRubyBaseContainerFrame.cpp
@@ -724,7 +724,7 @@ nsRubyBaseContainerFrame::PullOneColumn(nsLineLayout* aLineLayout,
   nsIFrame* nextBase = GetNextInFlowChild(aPullFrameState.mBase);
   MOZ_ASSERT(!nextBase || nextBase->GetType() == nsGkAtoms::rubyBaseFrame);
   aColumn.mBaseFrame = static_cast<nsRubyBaseFrame*>(nextBase);
-  aIsComplete = !aColumn.mBaseFrame;
+  bool foundFrame = !!aColumn.mBaseFrame;
   bool pullingIntraLevelWhitespace =
     aColumn.mBaseFrame && aColumn.mBaseFrame->IsIntraLevelWhitespace();
 
@@ -735,13 +735,17 @@ nsRubyBaseContainerFrame::PullOneColumn(nsLineLayout* aLineLayout,
     MOZ_ASSERT(!nextText || nextText->GetType() == nsGkAtoms::rubyTextFrame);
     nsRubyTextFrame* textFrame = static_cast<nsRubyTextFrame*>(nextText);
     aColumn.mTextFrames.AppendElement(textFrame);
-    // If there exists any frame in continations, we haven't
-    // completed the reflow process.
-    aIsComplete = aIsComplete && !nextText;
+    foundFrame = foundFrame || nextText;
     if (nextText && !pullingIntraLevelWhitespace) {
       pullingIntraLevelWhitespace = textFrame->IsIntraLevelWhitespace();
     }
   }
+  // If there exists any frame in continations, we haven't
+  // completed the reflow process.
+  aIsComplete = !foundFrame;
+  if (!foundFrame) {
+    return;
+  }
 
   aColumn.mIsIntraLevelWhitespace = pullingIntraLevelWhitespace;
   if (pullingIntraLevelWhitespace) {
@@ -757,6 +761,31 @@ nsRubyBaseContainerFrame::PullOneColumn(nsLineLayout* aLineLayout,
         textFrame = nullptr;
       }
     }
+  } else {
+    // We are not pulling an intra-level whitespace, which means all
+    // elements we are going to pull can have non-whitespace content,
+    // which may contain float which we need to reparent.
+    nsBlockFrame* oldFloatCB = nullptr;
+    for (nsIFrame* frame : aColumn) {
+      oldFloatCB = nsLayoutUtils::GetFloatContainingBlock(frame);
+      break;
+    }
+#ifdef DEBUG
+    MOZ_ASSERT(oldFloatCB, "Must have found a float containing block");
+    for (nsIFrame* frame : aColumn) {
+      MOZ_ASSERT(nsLayoutUtils::GetFloatContainingBlock(frame) == oldFloatCB,
+                 "All frames in the same ruby column should share "
+                 "the same old float containing block");
+    }
+#endif
+    nsBlockFrame* newFloatCB =
+      nsLayoutUtils::GetAsBlock(aLineLayout->LineContainerFrame());
+    MOZ_ASSERT(newFloatCB, "Must have a float containing block");
+    if (oldFloatCB != newFloatCB) {
+      for (nsIFrame* frame : aColumn) {
+        newFloatCB->ReparentFloats(frame, oldFloatCB, false);
+      }
+    }
   }
 
   // Pull the frames of this column.
diff --git a/layout/generic/nsRubyFrame.cpp b/layout/generic/nsRubyFrame.cpp
index 9b55ae973d..5fc54cfae3 100644
--- a/layout/generic/nsRubyFrame.cpp
+++ b/layout/generic/nsRubyFrame.cpp
@@ -142,7 +142,8 @@ nsRubyFrame::Reflow(nsPresContext* aPresContext,
 
   ContinuationTraversingState pullState(this);
   while (aStatus == NS_FRAME_COMPLETE) {
-    nsRubyBaseContainerFrame* baseContainer = PullOneSegment(pullState);
+    nsRubyBaseContainerFrame* baseContainer =
+      PullOneSegment(aReflowState.mLineLayout, pullState);
     if (!baseContainer) {
       // No more continuations after, finish now.
       break;
@@ -349,15 +350,21 @@ nsRubyFrame::ReflowSegment(nsPresContext* aPresContext,
 }
 
 nsRubyBaseContainerFrame*
-nsRubyFrame::PullOneSegment(ContinuationTraversingState& aState)
+nsRubyFrame::PullOneSegment(const nsLineLayout* aLineLayout,
+                            ContinuationTraversingState& aState)
 {
   // Pull a ruby base container
-  nsIFrame* baseFrame = PullNextInFlowChild(aState);
+  nsIFrame* baseFrame = GetNextInFlowChild(aState);
   if (!baseFrame) {
     return nullptr;
   }
   MOZ_ASSERT(baseFrame->GetType() == nsGkAtoms::rubyBaseContainerFrame);
 
+  // Get the float containing block of the base frame before we pull it.
+  nsBlockFrame* oldFloatCB =
+    nsLayoutUtils::GetFloatContainingBlock(baseFrame);
+  PullNextInFlowChild(aState);
+
   // Pull all ruby text containers following the base container
   nsIFrame* nextFrame;
   while ((nextFrame = GetNextInFlowChild(aState)) != nullptr &&
@@ -365,5 +372,12 @@ nsRubyFrame::PullOneSegment(ContinuationTraversingState& aState)
     PullNextInFlowChild(aState);
   }
 
+  if (nsBlockFrame* newFloatCB =
+      nsLayoutUtils::GetAsBlock(aLineLayout->LineContainerFrame())) {
+    if (oldFloatCB && oldFloatCB != newFloatCB) {
+      newFloatCB->ReparentFloats(baseFrame, oldFloatCB, true);
+    }
+  }
+
   return static_cast<nsRubyBaseContainerFrame*>(baseFrame);
 }
diff --git a/layout/generic/nsRubyFrame.h b/layout/generic/nsRubyFrame.h
index ab84de7326..125c08afac 100644
--- a/layout/generic/nsRubyFrame.h
+++ b/layout/generic/nsRubyFrame.h
@@ -62,7 +62,8 @@ protected:
                      nsRubyBaseContainerFrame* aBaseContainer,
                      nsReflowStatus& aStatus);
 
-  nsRubyBaseContainerFrame* PullOneSegment(ContinuationTraversingState& aState);
+  nsRubyBaseContainerFrame* PullOneSegment(const nsLineLayout* aLineLayout,
+                                           ContinuationTraversingState& aState);
 
   // The leading required to put the annotations.
   // They are not initialized until the first reflow.
diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
index 62649e7123..706e497785 100644
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -183,14 +183,14 @@ TabWidthStore::ApplySpacing(gfxTextRun::PropertyProvider::Spacing *aSpacing,
   }
 }
 
-NS_DECLARE_FRAME_PROPERTY(TabWidthProperty, DeleteValue<TabWidthStore>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(TabWidthProperty, TabWidthStore)
 
-NS_DECLARE_FRAME_PROPERTY(OffsetToFrameProperty, nullptr)
+NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(OffsetToFrameProperty, nsTextFrame)
 
 // text runs are destroyed by the text run cache
-NS_DECLARE_FRAME_PROPERTY(UninflatedTextRunProperty, nullptr)
+NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(UninflatedTextRunProperty, gfxTextRun)
 
-NS_DECLARE_FRAME_PROPERTY(FontSizeInflationProperty, nullptr)
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(FontSizeInflationProperty, float)
 
 class GlyphObserver : public gfxFont::GlyphChangeObserver {
 public:
@@ -207,8 +207,8 @@ private:
  * The only reason this list is in a property is to automatically destroy the
  * list when the frame is deleted, unregistering the observers.
  */
-NS_DECLARE_FRAME_PROPERTY(TextFrameGlyphObservers,
-                          DeleteValue<nsTArray<nsAutoPtr<GlyphObserver>>>);
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(TextFrameGlyphObservers,
+                                    nsTArray<nsAutoPtr<GlyphObserver>>)
 
 static const nsFrameState TEXT_REFLOW_FLAGS =
    TEXT_FIRST_LETTER |
@@ -4218,11 +4218,11 @@ nsContinuingTextFrame::Init(nsIContent*       aContent,
     FramePropertyTable *propTable = PresContext()->PropertyTable();
     // Get all the properties from the prev-in-flow first to take
     // advantage of the propTable's cache and simplify the assertion below
-    void* embeddingLevel =
+    auto embeddingLevel =
       propTable->Get(aPrevInFlow, nsBidi::EmbeddingLevelProperty());
-    void* baseLevel =
+    auto baseLevel =
       propTable->Get(aPrevInFlow, nsBidi::BaseLevelProperty());
-    void* paragraphDepth =
+    auto paragraphDepth =
       propTable->Get(aPrevInFlow, nsBidi::ParagraphDepthProperty());
     propTable->Set(this, nsBidi::EmbeddingLevelProperty(), embeddingLevel);
     propTable->Set(this, nsBidi::BaseLevelProperty(), baseLevel);
@@ -4489,8 +4489,7 @@ nsTextFrame::InvalidateFrameWithRect(const nsRect& aRect, uint32_t aDisplayItemK
 gfxTextRun*
 nsTextFrame::GetUninflatedTextRun()
 {
-  return static_cast<gfxTextRun*>(
-           Properties().Get(UninflatedTextRunProperty()));
+  return Properties().Get(UninflatedTextRunProperty());
 }
 
 void
@@ -4966,9 +4965,8 @@ static nscoord
 LazyGetLineBaselineOffset(nsIFrame* aChildFrame, nsBlockFrame* aBlockFrame)
 {
   bool offsetFound;
-  nscoord offset = NS_PTR_TO_INT32(
-    aChildFrame->Properties().Get(nsIFrame::LineBaselineOffset(), &offsetFound)
-    );
+  nscoord offset = aChildFrame->Properties().Get(
+    nsIFrame::LineBaselineOffset(), &offsetFound);
 
   if (!offsetFound) {
     for (nsBlockFrame::line_iterator line = aBlockFrame->begin_lines(),
@@ -4980,15 +4978,12 @@ LazyGetLineBaselineOffset(nsIFrame* aChildFrame, nsBlockFrame* aBlockFrame)
         for (nsIFrame* lineFrame = line->mFirstChild;
              n > 0; lineFrame = lineFrame->GetNextSibling(), --n) {
           offset = lineBaseline - lineFrame->GetNormalPosition().y;
-          lineFrame->Properties().Set(nsIFrame::LineBaselineOffset(),
-                                      NS_INT32_TO_PTR(offset));
+          lineFrame->Properties().Set(nsIFrame::LineBaselineOffset(), offset);
         }
       }
     }
-    return NS_PTR_TO_INT32(
-    aChildFrame->Properties().Get(nsIFrame::LineBaselineOffset(), &offsetFound)
-    );
-
+    return aChildFrame->Properties().Get(
+      nsIFrame::LineBaselineOffset(), &offsetFound);
   } else {
     return offset;
   }
@@ -5180,7 +5175,7 @@ struct EmphasisMarkInfo
   gfxFloat baselineOffset;
 };
 
-NS_DECLARE_FRAME_PROPERTY(EmphasisMarkProperty, DeleteValue<EmphasisMarkInfo>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(EmphasisMarkProperty, EmphasisMarkInfo)
 
 static gfxTextRun*
 GenerateTextRunForEmphasisMarks(nsTextFrame* aFrame, nsFontMetrics* aFontMetrics,
@@ -6271,8 +6266,7 @@ nsTextFrame::DrawEmphasisMarks(gfxContext* aContext, WritingMode aWM,
                                const nscolor* aDecorationOverrideColor,
                                PropertyProvider& aProvider)
 {
-  auto info = static_cast<const EmphasisMarkInfo*>(
-    Properties().Get(EmphasisMarkProperty()));
+  const auto info = Properties().Get(EmphasisMarkProperty());
   if (!info) {
     return;
   }
@@ -7249,8 +7243,7 @@ nsTextFrame::GetChildFrameContainingOffset(int32_t   aContentOffset,
   int32_t offset = mContentOffset;
 
   // Try to look up the offset to frame property
-  nsTextFrame* cachedFrame = static_cast<nsTextFrame*>
-    (Properties().Get(OffsetToFrameProperty()));
+  nsTextFrame* cachedFrame = Properties().Get(OffsetToFrameProperty());
 
   if (cachedFrame) {
     f = cachedFrame;
@@ -7828,22 +7821,13 @@ FindStartAfterSkippingWhitespace(PropertyProvider* aProvider,
   return aIterator->GetSkippedOffset();
 }
 
-union VoidPtrOrFloat {
-  VoidPtrOrFloat() : p(nullptr) {}
-
-  void *p;
-  float f;
-};
-
 float
 nsTextFrame::GetFontSizeInflation() const
 {
   if (!HasFontSizeInflation()) {
     return 1.0f;
   }
-  VoidPtrOrFloat u;
-  u.p = Properties().Get(FontSizeInflationProperty());
-  return u.f;
+  return Properties().Get(FontSizeInflationProperty());
 }
 
 void
@@ -7858,9 +7842,7 @@ nsTextFrame::SetFontSizeInflation(float aInflation)
   }
 
   AddStateBits(TEXT_HAS_FONT_INFLATION);
-  VoidPtrOrFloat u;
-  u.f = aInflation;
-  Properties().Set(FontSizeInflationProperty(), u.p);
+  Properties().Set(FontSizeInflationProperty(), aInflation);
 }
 
 /* virtual */ 
@@ -9629,7 +9611,7 @@ nsTextFrame::UpdateOverflow()
   return FinishAndStoreOverflow(overflowAreas, GetSize());
 }
 
-NS_DECLARE_FRAME_PROPERTY(JustificationAssignmentProperty, nullptr)
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(JustificationAssignmentProperty, int32_t)
 
 void
 nsTextFrame::AssignJustificationGaps(
@@ -9639,14 +9621,13 @@ nsTextFrame::AssignJustificationGaps(
   static_assert(sizeof(aAssign) == 1,
                 "The encoding might be broken if JustificationAssignment "
                 "is larger than 1 byte");
-  Properties().Set(JustificationAssignmentProperty(), NS_INT32_TO_PTR(encoded));
+  Properties().Set(JustificationAssignmentProperty(), encoded);
 }
 
 mozilla::JustificationAssignment
 nsTextFrame::GetJustificationAssignment() const
 {
-  int32_t encoded =
-    NS_PTR_TO_INT32(Properties().Get(JustificationAssignmentProperty()));
+  int32_t encoded = Properties().Get(JustificationAssignmentProperty());
   mozilla::JustificationAssignment result;
   result.mGapsAtStart = encoded >> 8;
   result.mGapsAtEnd = encoded & 0xFF;
diff --git a/layout/mathml/nsMathMLContainerFrame.cpp b/layout/mathml/nsMathMLContainerFrame.cpp
index 27326d523a..b380078145 100644
--- a/layout/mathml/nsMathMLContainerFrame.cpp
+++ b/layout/mathml/nsMathMLContainerFrame.cpp
@@ -127,8 +127,8 @@ IsForeignChild(const nsIFrame* aFrame)
     aFrame->GetType() == nsGkAtoms::blockFrame;
 }
 
-NS_DECLARE_FRAME_PROPERTY(HTMLReflowMetricsProperty,
-                          DeleteValue<nsHTMLReflowMetrics>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(HTMLReflowMetricsProperty,
+                                    nsHTMLReflowMetrics)
 
 /* static */ void
 nsMathMLContainerFrame::SaveReflowAndBoundingMetricsFor(nsIFrame*                  aFrame,
@@ -149,8 +149,8 @@ nsMathMLContainerFrame::GetReflowAndBoundingMetricsFor(nsIFrame*            aFra
 {
   NS_PRECONDITION(aFrame, "null arg");
 
-  nsHTMLReflowMetrics *metrics = static_cast<nsHTMLReflowMetrics*>
-    (aFrame->Properties().Get(HTMLReflowMetricsProperty()));
+  nsHTMLReflowMetrics *metrics =
+    aFrame->Properties().Get(HTMLReflowMetricsProperty());
 
   // IMPORTANT: This function is only meant to be called in Place() methods
   // where it is assumed that SaveReflowAndBoundingMetricsFor has recorded the
diff --git a/layout/mathml/nsMathMLmtableFrame.cpp b/layout/mathml/nsMathMLmtableFrame.cpp
index 8b286823d7..959927086c 100644
--- a/layout/mathml/nsMathMLmtableFrame.cpp
+++ b/layout/mathml/nsMathMLmtableFrame.cpp
@@ -131,12 +131,12 @@ static nsresult ReportParseError(nsIFrame* aFrame, const char16_t* aAttribute,
 // stored in the property table. Row/Cell frames query the property table
 // to see what values apply to them.
 
-NS_DECLARE_FRAME_PROPERTY(RowAlignProperty, DeleteValue<nsTArray<int8_t>>)
-NS_DECLARE_FRAME_PROPERTY(RowLinesProperty, DeleteValue<nsTArray<int8_t>>)
-NS_DECLARE_FRAME_PROPERTY(ColumnAlignProperty, DeleteValue<nsTArray<int8_t>>)
-NS_DECLARE_FRAME_PROPERTY(ColumnLinesProperty, DeleteValue<nsTArray<int8_t>>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(RowAlignProperty, nsTArray<int8_t>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(RowLinesProperty, nsTArray<int8_t>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(ColumnAlignProperty, nsTArray<int8_t>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(ColumnLinesProperty, nsTArray<int8_t>)
 
-static const FramePropertyDescriptor*
+static const FramePropertyDescriptor<nsTArray<int8_t>>*
 AttributeToProperty(nsIAtom* aAttribute)
 {
   if (aAttribute == nsGkAtoms::rowalign_)
@@ -157,14 +157,14 @@ AttributeToProperty(nsIAtom* aAttribute)
  */
 static nsTArray<int8_t>*
 FindCellProperty(const nsIFrame* aCellFrame,
-                 const FramePropertyDescriptor* aFrameProperty)
+                 const FramePropertyDescriptor<nsTArray<int8_t>>* aFrameProperty)
 {
   const nsIFrame* currentFrame = aCellFrame;
   nsTArray<int8_t>* propertyData = nullptr;
 
   while (currentFrame) {
     FrameProperties props = currentFrame->Properties();
-    propertyData = static_cast<nsTArray<int8_t>*>(props.Get(aFrameProperty));
+    propertyData = props.Get(aFrameProperty);
     bool frameIsTable = (currentFrame->GetType() == nsGkAtoms::tableFrame);
 
     if (propertyData || frameIsTable)
diff --git a/layout/style/Declaration.cpp b/layout/style/Declaration.cpp
index 1881636ab8..c8a07a1c76 100644
--- a/layout/style/Declaration.cpp
+++ b/layout/style/Declaration.cpp
@@ -539,20 +539,20 @@ Declaration::GetValue(nsCSSProperty aProperty, nsAString& aValue,
                    origin->mValue.GetUnit() == eCSSUnit_Enumerated,
                    "should not have inherit/initial within list");
 
-        if (clip->mValue.GetIntValue() != NS_STYLE_BG_CLIP_BORDER ||
-            origin->mValue.GetIntValue() != NS_STYLE_BG_ORIGIN_PADDING) {
+        if (clip->mValue.GetIntValue() != NS_STYLE_IMAGELAYER_CLIP_BORDER ||
+            origin->mValue.GetIntValue() != NS_STYLE_IMAGELAYER_ORIGIN_PADDING) {
           MOZ_ASSERT(nsCSSProps::kKeywordTableTable[
                        eCSSProperty_background_origin] ==
-                     nsCSSProps::kBackgroundOriginKTable);
+                     nsCSSProps::kImageLayerOriginKTable);
           MOZ_ASSERT(nsCSSProps::kKeywordTableTable[
                        eCSSProperty_background_clip] ==
-                     nsCSSProps::kBackgroundOriginKTable);
-          static_assert(NS_STYLE_BG_CLIP_BORDER ==
-                        NS_STYLE_BG_ORIGIN_BORDER &&
-                        NS_STYLE_BG_CLIP_PADDING ==
-                        NS_STYLE_BG_ORIGIN_PADDING &&
-                        NS_STYLE_BG_CLIP_CONTENT ==
-                        NS_STYLE_BG_ORIGIN_CONTENT,
+                     nsCSSProps::kImageLayerOriginKTable);
+          static_assert(NS_STYLE_IMAGELAYER_CLIP_BORDER ==
+                        NS_STYLE_IMAGELAYER_ORIGIN_BORDER &&
+                        NS_STYLE_IMAGELAYER_CLIP_PADDING ==
+                        NS_STYLE_IMAGELAYER_ORIGIN_PADDING &&
+                        NS_STYLE_IMAGELAYER_CLIP_CONTENT ==
+                        NS_STYLE_IMAGELAYER_ORIGIN_CONTENT,
                         "bg-clip and bg-origin style constants must agree");
           aValue.Append(char16_t(' '));
           origin->mValue.AppendToString(eCSSProperty_background_origin, aValue,
diff --git a/layout/style/StyleAnimationValue.cpp b/layout/style/StyleAnimationValue.cpp
index a53bc73e83..c286726cd4 100644
--- a/layout/style/StyleAnimationValue.cpp
+++ b/layout/style/StyleAnimationValue.cpp
@@ -2923,7 +2923,7 @@ StyleCoordToCSSValue(const nsStyleCoord& aCoord, nsCSSValue& aCSSValue)
 }
 
 static void
-SetPositionValue(const nsStyleBackground::Position& aPos, nsCSSValue& aCSSValue)
+SetPositionValue(const nsStyleImageLayers::Position& aPos, nsCSSValue& aCSSValue)
 {
   RefPtr<nsCSSValue::Array> posArray = nsCSSValue::Array::Create(4);
   aCSSValue.SetArrayValue(posArray.get(), eCSSUnit_Array);
@@ -3292,12 +3292,12 @@ StyleAnimationValue::ExtractComputedValue(nsCSSProperty aProperty,
             static_cast<const nsStyleBackground*>(styleStruct);
           nsAutoPtr<nsCSSValueList> result;
           nsCSSValueList **resultTail = getter_Transfers(result);
-          MOZ_ASSERT(bg->mPositionCount > 0, "unexpected count");
-          for (uint32_t i = 0, i_end = bg->mPositionCount; i != i_end; ++i) {
+          MOZ_ASSERT(bg->mLayers.mPositionCount > 0, "unexpected count");
+          for (uint32_t i = 0, i_end = bg->mLayers.mPositionCount; i != i_end; ++i) {
             nsCSSValueList *item = new nsCSSValueList;
             *resultTail = item;
             resultTail = &item->mNext;
-            SetPositionValue(bg->mLayers[i].mPosition, item->mValue);
+            SetPositionValue(bg->mLayers.mLayers[i].mPosition, item->mValue);
           }
 
           aComputedValue.SetAndAdoptCSSValueListValue(result.forget(),
@@ -3310,23 +3310,23 @@ StyleAnimationValue::ExtractComputedValue(nsCSSProperty aProperty,
             static_cast<const nsStyleBackground*>(styleStruct);
           nsAutoPtr<nsCSSValuePairList> result;
           nsCSSValuePairList **resultTail = getter_Transfers(result);
-          MOZ_ASSERT(bg->mSizeCount > 0, "unexpected count");
-          for (uint32_t i = 0, i_end = bg->mSizeCount; i != i_end; ++i) {
+          MOZ_ASSERT(bg->mLayers.mSizeCount > 0, "unexpected count");
+          for (uint32_t i = 0, i_end = bg->mLayers.mSizeCount; i != i_end; ++i) {
             nsCSSValuePairList *item = new nsCSSValuePairList;
             *resultTail = item;
             resultTail = &item->mNext;
 
-            const nsStyleBackground::Size &size = bg->mLayers[i].mSize;
+            const nsStyleImageLayers::Size &size = bg->mLayers.mLayers[i].mSize;
             switch (size.mWidthType) {
-              case nsStyleBackground::Size::eContain:
-              case nsStyleBackground::Size::eCover:
+              case nsStyleImageLayers::Size::eContain:
+              case nsStyleImageLayers::Size::eCover:
                 item->mXValue.SetIntValue(size.mWidthType,
                                           eCSSUnit_Enumerated);
                 break;
-              case nsStyleBackground::Size::eAuto:
+              case nsStyleImageLayers::Size::eAuto:
                 item->mXValue.SetAutoValue();
                 break;
-              case nsStyleBackground::Size::eLengthPercentage:
+              case nsStyleImageLayers::Size::eLengthPercentage:
                 // XXXbz is there a good reason we can't just
                 // SetCalcValue(&size.mWidth, item->mXValue) here?
                 if (!size.mWidth.mHasPercent &&
@@ -3346,14 +3346,14 @@ StyleAnimationValue::ExtractComputedValue(nsCSSProperty aProperty,
             }
 
             switch (size.mHeightType) {
-              case nsStyleBackground::Size::eContain:
-              case nsStyleBackground::Size::eCover:
+              case nsStyleImageLayers::Size::eContain:
+              case nsStyleImageLayers::Size::eCover:
                 // leave it null
                 break;
-              case nsStyleBackground::Size::eAuto:
+              case nsStyleImageLayers::Size::eAuto:
                 item->mYValue.SetAutoValue();
                 break;
-              case nsStyleBackground::Size::eLengthPercentage:
+              case nsStyleImageLayers::Size::eLengthPercentage:
                 // XXXbz is there a good reason we can't just
                 // SetCalcValue(&size.mHeight, item->mYValue) here?
                 if (!size.mHeight.mHasPercent &&
diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index 4801f84698..60c4639f62 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -852,7 +852,7 @@ protected:
   // Property specific parsing routines
   bool ParseBackground();
 
-  struct BackgroundParseState {
+  struct ImageLayersShorthandParseState {
     nsCSSValue&  mColor;
     nsCSSValueList* mImage;
     nsCSSValuePairList* mRepeat;
@@ -861,23 +861,27 @@ protected:
     nsCSSValueList* mOrigin;
     nsCSSValueList* mPosition;
     nsCSSValuePairList* mSize;
-    BackgroundParseState(
+    nsCSSValueList* mComposite;
+    nsCSSValueList* mMode;
+    ImageLayersShorthandParseState(
         nsCSSValue& aColor, nsCSSValueList* aImage, nsCSSValuePairList* aRepeat,
         nsCSSValueList* aAttachment, nsCSSValueList* aClip,
         nsCSSValueList* aOrigin, nsCSSValueList* aPosition,
-        nsCSSValuePairList* aSize) :
+        nsCSSValuePairList* aSize, nsCSSValueList* aComposite,
+        nsCSSValueList* aMode) :
         mColor(aColor), mImage(aImage), mRepeat(aRepeat),
         mAttachment(aAttachment), mClip(aClip), mOrigin(aOrigin),
-        mPosition(aPosition), mSize(aSize) {};
+        mPosition(aPosition), mSize(aSize), mComposite(aComposite),
+        mMode(aMode) {};
   };
 
-  bool IsFunctionTokenValidForBackgroundImage(const nsCSSToken& aToken) const;
-  bool ParseBackgroundItem(BackgroundParseState& aState);
+  bool IsFunctionTokenValidForImageLayerImage(const nsCSSToken& aToken) const;
+  bool ParseBackgroundItem(ImageLayersShorthandParseState& aState);
 
   bool ParseValueList(nsCSSProperty aPropID); // a single value prop-id
-  bool ParseBackgroundRepeat();
-  bool ParseBackgroundRepeatValues(nsCSSValuePair& aValue);
-  bool ParseBackgroundPosition();
+  bool ParseImageLayerRepeat(nsCSSProperty aPropID);
+  bool ParseImageLayerRepeatValues(nsCSSValuePair& aValue);
+  bool ParseImageLayerPosition(nsCSSProperty aPropID);
 
   // ParseBoxPositionValues parses the CSS 2.1 background-position syntax,
   // which is still used by some properties. See ParsePositionValue
@@ -889,8 +893,8 @@ protected:
   // the 'background-position' property.
   bool ParsePositionValue(nsCSSValue& aOut);
 
-  bool ParseBackgroundSize();
-  bool ParseBackgroundSizeValues(nsCSSValuePair& aOut);
+  bool ParseImageLayerSize(nsCSSProperty aPropID);
+  bool ParseImageLayerSizeValues(nsCSSValuePair& aOut);
   bool ParseBorderColor();
   bool ParseBorderColors(nsCSSProperty aProperty);
   void SetBorderImageInitialValues();
@@ -9867,13 +9871,13 @@ IsBoxPositionStrictlyEdgeKeywords(nsCSSValuePair& aPosition)
   const nsCSSValue& xValue = aPosition.mXValue;
   const nsCSSValue& yValue = aPosition.mYValue;
   return (xValue.GetUnit() == eCSSUnit_Enumerated &&
-          (xValue.GetIntValue() & (NS_STYLE_BG_POSITION_LEFT |
-                                   NS_STYLE_BG_POSITION_CENTER |
-                                   NS_STYLE_BG_POSITION_RIGHT)) &&
+          (xValue.GetIntValue() & (NS_STYLE_IMAGELAYER_POSITION_LEFT |
+                                   NS_STYLE_IMAGELAYER_POSITION_CENTER |
+                                   NS_STYLE_IMAGELAYER_POSITION_RIGHT)) &&
           yValue.GetUnit() == eCSSUnit_Enumerated &&
-          (yValue.GetIntValue() & (NS_STYLE_BG_POSITION_TOP |
-                                   NS_STYLE_BG_POSITION_CENTER |
-                                   NS_STYLE_BG_POSITION_BOTTOM)));
+          (yValue.GetIntValue() & (NS_STYLE_IMAGELAYER_POSITION_TOP |
+                                   NS_STYLE_IMAGELAYER_POSITION_CENTER |
+                                   NS_STYLE_IMAGELAYER_POSITION_BOTTOM)));
 }
 
 // <gradient>
@@ -10208,7 +10212,7 @@ CSSParserImpl::IsLegacyGradientLine(const nsCSSTokenType& aType,
     nsCSSKeyword kw = nsCSSKeywords::LookupKeyword(aId);
     int32_t junk;
     if (kw != eCSSKeyword_UNKNOWN &&
-        nsCSSProps::FindKeyword(kw, nsCSSProps::kBackgroundPositionKTable,
+        nsCSSProps::FindKeyword(kw, nsCSSProps::kImageLayerPositionKTable,
                                 junk)) {
       haveGradientLine = true;
     }
@@ -10551,13 +10555,13 @@ CSSParserImpl::FinalizeLinearWebkitGradient(nsCSSValueGradient* aGradient,
   // this as a horizontal gradient progressing towards the center of the left
   // or right side.
   if (aStartPoint.mYValue == aEndPoint.mYValue) {
-    aGradient->mBgPos.mYValue.SetIntValue(NS_STYLE_BG_POSITION_CENTER,
+    aGradient->mBgPos.mYValue.SetIntValue(NS_STYLE_IMAGELAYER_POSITION_CENTER,
                                           eCSSUnit_Enumerated);
     if (IsWebkitGradientCoordLarger(aStartPoint.mXValue, aEndPoint.mXValue)) {
-      aGradient->mBgPos.mXValue.SetIntValue(NS_STYLE_BG_POSITION_LEFT,
+      aGradient->mBgPos.mXValue.SetIntValue(NS_STYLE_IMAGELAYER_POSITION_LEFT,
                                             eCSSUnit_Enumerated);
     } else {
-      aGradient->mBgPos.mXValue.SetIntValue(NS_STYLE_BG_POSITION_RIGHT,
+      aGradient->mBgPos.mXValue.SetIntValue(NS_STYLE_IMAGELAYER_POSITION_RIGHT,
                                             eCSSUnit_Enumerated);
     }
     return;
@@ -10567,13 +10571,13 @@ CSSParserImpl::FinalizeLinearWebkitGradient(nsCSSValueGradient* aGradient,
   // this as a horizontal gradient progressing towards the center of the top
   // or bottom side.
   if (aStartPoint.mXValue == aEndPoint.mXValue) {
-    aGradient->mBgPos.mXValue.SetIntValue(NS_STYLE_BG_POSITION_CENTER,
+    aGradient->mBgPos.mXValue.SetIntValue(NS_STYLE_IMAGELAYER_POSITION_CENTER,
                                           eCSSUnit_Enumerated);
     if (IsWebkitGradientCoordLarger(aStartPoint.mYValue, aEndPoint.mYValue)) {
-      aGradient->mBgPos.mYValue.SetIntValue(NS_STYLE_BG_POSITION_TOP,
+      aGradient->mBgPos.mYValue.SetIntValue(NS_STYLE_IMAGELAYER_POSITION_TOP,
                                             eCSSUnit_Enumerated);
     } else {
-      aGradient->mBgPos.mYValue.SetIntValue(NS_STYLE_BG_POSITION_BOTTOM,
+      aGradient->mBgPos.mYValue.SetIntValue(NS_STYLE_IMAGELAYER_POSITION_BOTTOM,
                                             eCSSUnit_Enumerated);
     }
     return;
@@ -11310,11 +11314,11 @@ CSSParserImpl::ParsePropertyByFunction(nsCSSProperty aPropID)
   case eCSSProperty_background:
     return ParseBackground();
   case eCSSProperty_background_repeat:
-    return ParseBackgroundRepeat();
+    return ParseImageLayerRepeat(eCSSProperty_background_repeat);
   case eCSSProperty_background_position:
-    return ParseBackgroundPosition();
+    return ParseImageLayerPosition(eCSSProperty_background_position);
   case eCSSProperty_background_size:
-    return ParseBackgroundSize();
+    return ParseImageLayerSize(eCSSProperty_background_size);
   case eCSSProperty_border:
     return ParseBorderSide(kBorderTopIDs, true);
   case eCSSProperty_border_color:
@@ -11497,11 +11501,11 @@ CSSParserImpl::ParsePropertyByFunction(nsCSSProperty aPropID)
 }
 
 // Bits used in determining which background position info we have
-#define BG_CENTER  NS_STYLE_BG_POSITION_CENTER
-#define BG_TOP     NS_STYLE_BG_POSITION_TOP
-#define BG_BOTTOM  NS_STYLE_BG_POSITION_BOTTOM
-#define BG_LEFT    NS_STYLE_BG_POSITION_LEFT
-#define BG_RIGHT   NS_STYLE_BG_POSITION_RIGHT
+#define BG_CENTER  NS_STYLE_IMAGELAYER_POSITION_CENTER
+#define BG_TOP     NS_STYLE_IMAGELAYER_POSITION_TOP
+#define BG_BOTTOM  NS_STYLE_IMAGELAYER_POSITION_BOTTOM
+#define BG_LEFT    NS_STYLE_IMAGELAYER_POSITION_LEFT
+#define BG_RIGHT   NS_STYLE_IMAGELAYER_POSITION_RIGHT
 #define BG_CTB    (BG_CENTER | BG_TOP | BG_BOTTOM)
 #define BG_TB     (BG_TOP | BG_BOTTOM)
 #define BG_CLR    (BG_CENTER | BG_LEFT | BG_RIGHT)
@@ -11719,21 +11723,21 @@ CSSParserImpl::ParseFontDescriptorValue(nsCSSFontDesc aDescID,
 static nsCSSValue
 BoxPositionMaskToCSSValue(int32_t aMask, bool isX)
 {
-  int32_t val = NS_STYLE_BG_POSITION_CENTER;
+  int32_t val = NS_STYLE_IMAGELAYER_POSITION_CENTER;
   if (isX) {
     if (aMask & BG_LEFT) {
-      val = NS_STYLE_BG_POSITION_LEFT;
+      val = NS_STYLE_IMAGELAYER_POSITION_LEFT;
     }
     else if (aMask & BG_RIGHT) {
-      val = NS_STYLE_BG_POSITION_RIGHT;
+      val = NS_STYLE_IMAGELAYER_POSITION_RIGHT;
     }
   }
   else {
     if (aMask & BG_TOP) {
-      val = NS_STYLE_BG_POSITION_TOP;
+      val = NS_STYLE_IMAGELAYER_POSITION_TOP;
     }
     else if (aMask & BG_BOTTOM) {
-      val = NS_STYLE_BG_POSITION_BOTTOM;
+      val = NS_STYLE_IMAGELAYER_POSITION_BOTTOM;
     }
   }
 
@@ -11759,12 +11763,13 @@ CSSParserImpl::ParseBackground()
     return true;
   }
 
-  nsCSSValue image, repeat, attachment, clip, origin, position, size;
-  BackgroundParseState state(color, image.SetListValue(), 
-                             repeat.SetPairListValue(),
-                             attachment.SetListValue(), clip.SetListValue(),
-                             origin.SetListValue(), position.SetListValue(),
-                             size.SetPairListValue());
+  nsCSSValue image, repeat, attachment, clip, origin, position, size, composite, mode;
+  ImageLayersShorthandParseState state(color, image.SetListValue(),
+                                       repeat.SetPairListValue(),
+                                       attachment.SetListValue(), clip.SetListValue(),
+                                       origin.SetListValue(), position.SetListValue(),
+                                       size.SetPairListValue(), composite.SetListValue(),
+                                       mode.SetListValue());
 
   for (;;) {
     if (!ParseBackgroundItem(state)) {
@@ -11814,7 +11819,7 @@ CSSParserImpl::ParseBackground()
 // Helper for ParseBackgroundItem. Returns true if the passed-in nsCSSToken is
 // a function which is accepted for background-image.
 bool
-CSSParserImpl::IsFunctionTokenValidForBackgroundImage(
+CSSParserImpl::IsFunctionTokenValidForImageLayerImage(
   const nsCSSToken& aToken) const
 {
   MOZ_ASSERT(aToken.mType == eCSSToken_Function,
@@ -11842,20 +11847,20 @@ CSSParserImpl::IsFunctionTokenValidForBackgroundImage(
 
 // Parse one item of the background shorthand property.
 bool
-CSSParserImpl::ParseBackgroundItem(CSSParserImpl::BackgroundParseState& aState)
+CSSParserImpl::ParseBackgroundItem(CSSParserImpl::ImageLayersShorthandParseState& aState)
 
 {
   // Fill in the values that the shorthand will set if we don't find
   // other values.
   aState.mImage->mValue.SetNoneValue();
-  aState.mRepeat->mXValue.SetIntValue(NS_STYLE_BG_REPEAT_REPEAT,
+  aState.mRepeat->mXValue.SetIntValue(NS_STYLE_IMAGELAYER_REPEAT_REPEAT,
                                       eCSSUnit_Enumerated);
   aState.mRepeat->mYValue.Reset();
-  aState.mAttachment->mValue.SetIntValue(NS_STYLE_BG_ATTACHMENT_SCROLL,
+  aState.mAttachment->mValue.SetIntValue(NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL,
                                          eCSSUnit_Enumerated);
-  aState.mClip->mValue.SetIntValue(NS_STYLE_BG_CLIP_BORDER,
+  aState.mClip->mValue.SetIntValue(NS_STYLE_IMAGELAYER_CLIP_BORDER,
                                    eCSSUnit_Enumerated);
-  aState.mOrigin->mValue.SetIntValue(NS_STYLE_BG_ORIGIN_PADDING,
+  aState.mOrigin->mValue.SetIntValue(NS_STYLE_IMAGELAYER_ORIGIN_PADDING,
                                      eCSSUnit_Enumerated);
   RefPtr<nsCSSValue::Array> positionArr = nsCSSValue::Array::Create(4);
   aState.mPosition->mValue.SetArrayValue(positionArr, eCSSUnit_Array);
@@ -11899,7 +11904,7 @@ CSSParserImpl::ParseBackgroundItem(CSSParserImpl::BackgroundParseState& aState)
           return false;
         }
       } else if (nsCSSProps::FindKeyword(keyword,
-                   nsCSSProps::kBackgroundAttachmentKTable, dummy)) {
+                   nsCSSProps::kImageLayerAttachmentKTable, dummy)) {
         if (haveAttach)
           return false;
         haveAttach = true;
@@ -11910,19 +11915,19 @@ CSSParserImpl::ParseBackgroundItem(CSSParserImpl::BackgroundParseState& aState)
           return false;
         }
       } else if (nsCSSProps::FindKeyword(keyword,
-                   nsCSSProps::kBackgroundRepeatKTable, dummy)) {
+                   nsCSSProps::kImageLayerRepeatKTable, dummy)) {
         if (haveRepeat)
           return false;
         haveRepeat = true;
         nsCSSValuePair scratch;
-        if (!ParseBackgroundRepeatValues(scratch)) {
+        if (!ParseImageLayerRepeatValues(scratch)) {
           NS_NOTREACHED("should be able to parse");
           return false;
         }
         aState.mRepeat->mXValue = scratch.mXValue;
         aState.mRepeat->mYValue = scratch.mYValue;
       } else if (nsCSSProps::FindKeyword(keyword,
-                   nsCSSProps::kBackgroundPositionKTable, dummy)) {
+                   nsCSSProps::kImageLayerPositionKTable, dummy)) {
         if (havePositionAndSize)
           return false;
         havePositionAndSize = true;
@@ -11931,14 +11936,14 @@ CSSParserImpl::ParseBackgroundItem(CSSParserImpl::BackgroundParseState& aState)
         }
         if (ExpectSymbol('/', true)) {
           nsCSSValuePair scratch;
-          if (!ParseBackgroundSizeValues(scratch)) {
+          if (!ParseImageLayerSizeValues(scratch)) {
             return false;
           }
           aState.mSize->mXValue = scratch.mXValue;
           aState.mSize->mYValue = scratch.mYValue;
         }
       } else if (nsCSSProps::FindKeyword(keyword,
-                   nsCSSProps::kBackgroundOriginKTable, dummy)) {
+                   nsCSSProps::kImageLayerOriginKTable, dummy)) {
         if (haveOrigin)
           return false;
         haveOrigin = true;
@@ -11955,16 +11960,16 @@ CSSParserImpl::ParseBackgroundItem(CSSParserImpl::BackgroundParseState& aState)
         // 'background-clip' and 'background-origin' use the same keyword table
         MOZ_ASSERT(nsCSSProps::kKeywordTableTable[
                      eCSSProperty_background_origin] ==
-                   nsCSSProps::kBackgroundOriginKTable);
+                   nsCSSProps::kImageLayerOriginKTable);
         MOZ_ASSERT(nsCSSProps::kKeywordTableTable[
                      eCSSProperty_background_clip] ==
-                   nsCSSProps::kBackgroundOriginKTable);
-        static_assert(NS_STYLE_BG_CLIP_BORDER ==
-                      NS_STYLE_BG_ORIGIN_BORDER &&
-                      NS_STYLE_BG_CLIP_PADDING ==
-                      NS_STYLE_BG_ORIGIN_PADDING &&
-                      NS_STYLE_BG_CLIP_CONTENT ==
-                      NS_STYLE_BG_ORIGIN_CONTENT,
+                   nsCSSProps::kImageLayerOriginKTable);
+        static_assert(NS_STYLE_IMAGELAYER_CLIP_BORDER ==
+                      NS_STYLE_IMAGELAYER_ORIGIN_BORDER &&
+                      NS_STYLE_IMAGELAYER_CLIP_PADDING ==
+                      NS_STYLE_IMAGELAYER_ORIGIN_PADDING &&
+                      NS_STYLE_IMAGELAYER_CLIP_CONTENT ==
+                      NS_STYLE_IMAGELAYER_ORIGIN_CONTENT,
                       "bg-clip and bg-origin style constants must agree");
 
         CSSParseResult result =
@@ -11991,7 +11996,7 @@ CSSParserImpl::ParseBackgroundItem(CSSParserImpl::BackgroundParseState& aState)
       }
     } else if (tt == eCSSToken_URL ||
                (tt == eCSSToken_Function &&
-                IsFunctionTokenValidForBackgroundImage(mToken))) {
+                IsFunctionTokenValidForImageLayerImage(mToken))) {
       if (haveImage)
         return false;
       haveImage = true;
@@ -12014,7 +12019,7 @@ CSSParserImpl::ParseBackgroundItem(CSSParserImpl::BackgroundParseState& aState)
       }
       if (ExpectSymbol('/', true)) {
         nsCSSValuePair scratch;
-        if (!ParseBackgroundSizeValues(scratch)) {
+        if (!ParseImageLayerSizeValues(scratch)) {
           return false;
         }
         aState.mSize->mXValue = scratch.mXValue;
@@ -12039,7 +12044,7 @@ CSSParserImpl::ParseBackgroundItem(CSSParserImpl::BackgroundParseState& aState)
 }
 
 // This function is very similar to ParseScrollSnapCoordinate,
-// ParseBackgroundPosition, and ParseBackgroundSize.
+// ParseImageLayerPosition, and ParseBackgroundSize.
 bool
 CSSParserImpl::ParseValueList(nsCSSProperty aPropID)
 {
@@ -12065,13 +12070,13 @@ CSSParserImpl::ParseValueList(nsCSSProperty aPropID)
 }
 
 bool
-CSSParserImpl::ParseBackgroundRepeat()
+CSSParserImpl::ParseImageLayerRepeat(nsCSSProperty aPropID)
 {
   nsCSSValue value;
   // 'initial', 'inherit' and 'unset' stand alone, no list permitted.
   if (!ParseSingleTokenVariant(value, VARIANT_INHERIT, nullptr)) {
     nsCSSValuePair valuePair;
-    if (!ParseBackgroundRepeatValues(valuePair)) {
+    if (!ParseImageLayerRepeatValues(valuePair)) {
       return false;
     }
     nsCSSValuePairList* item = value.SetPairListValue();
@@ -12081,7 +12086,7 @@ CSSParserImpl::ParseBackgroundRepeat()
       if (!ExpectSymbol(',', true)) {
         break;
       }
-      if (!ParseBackgroundRepeatValues(valuePair)) {
+      if (!ParseImageLayerRepeatValues(valuePair)) {
         return false;
       }
       item->mNext = new nsCSSValuePairList;
@@ -12089,36 +12094,36 @@ CSSParserImpl::ParseBackgroundRepeat()
     }
   }
 
-  AppendValue(eCSSProperty_background_repeat, value);
+  AppendValue(aPropID, value);
   return true;
 }
 
 bool
-CSSParserImpl::ParseBackgroundRepeatValues(nsCSSValuePair& aValue) 
+CSSParserImpl::ParseImageLayerRepeatValues(nsCSSValuePair& aValue)
 {
   nsCSSValue& xValue = aValue.mXValue;
   nsCSSValue& yValue = aValue.mYValue;
-  
-  if (ParseEnum(xValue, nsCSSProps::kBackgroundRepeatKTable)) {
+
+  if (ParseEnum(xValue, nsCSSProps::kImageLayerRepeatKTable)) {
     int32_t value = xValue.GetIntValue();
     // For single values set yValue as eCSSUnit_Null.
-    if (value == NS_STYLE_BG_REPEAT_REPEAT_X ||
-        value == NS_STYLE_BG_REPEAT_REPEAT_Y ||
-        !ParseEnum(yValue, nsCSSProps::kBackgroundRepeatPartKTable)) {
+    if (value == NS_STYLE_IMAGELAYER_REPEAT_REPEAT_X ||
+        value == NS_STYLE_IMAGELAYER_REPEAT_REPEAT_Y ||
+        !ParseEnum(yValue, nsCSSProps::kImageLayerRepeatPartKTable)) {
       // the caller will fail cases like "repeat-x no-repeat"
       // by expecting a list separator or an end property.
       yValue.Reset();
     }
     return true;
   }
-  
+
   return false;
 }
 
 // This function is very similar to ParseScrollSnapCoordinate,
 // ParseBackgroundList, and ParseBackgroundSize.
 bool
-CSSParserImpl::ParseBackgroundPosition()
+CSSParserImpl::ParseImageLayerPosition(nsCSSProperty aPropID)
 {
   nsCSSValue value;
   // 'initial', 'inherit' and 'unset' stand alone, no list permitted.
@@ -12140,7 +12145,7 @@ CSSParserImpl::ParseBackgroundPosition()
       item = item->mNext;
     }
   }
-  AppendValue(eCSSProperty_background_position, value);
+  AppendValue(aPropID, value);
   return true;
 }
 
@@ -12190,7 +12195,7 @@ bool CSSParserImpl::ParseBoxPositionValues(nsCSSValuePair &aOut,
       return true;
     }
 
-    if (ParseEnum(yValue, nsCSSProps::kBackgroundPositionKTable)) {
+    if (ParseEnum(yValue, nsCSSProps::kImageLayerPositionKTable)) {
       int32_t yVal = yValue.GetIntValue();
       if (!(yVal & BG_CTB)) {
         // The second keyword can only be 'center', 'top', or 'bottom'
@@ -12213,10 +12218,10 @@ bool CSSParserImpl::ParseBoxPositionValues(nsCSSValuePair &aOut,
   // any duplicate keywords other than center. We try to get two
   // keywords but it's okay if there is only one.
   int32_t mask = 0;
-  if (ParseEnum(xValue, nsCSSProps::kBackgroundPositionKTable)) {
+  if (ParseEnum(xValue, nsCSSProps::kImageLayerPositionKTable)) {
     int32_t bit = xValue.GetIntValue();
     mask |= bit;
-    if (ParseEnum(xValue, nsCSSProps::kBackgroundPositionKTable)) {
+    if (ParseEnum(xValue, nsCSSProps::kImageLayerPositionKTable)) {
       bit = xValue.GetIntValue();
       if (mask & (bit & ~BG_CENTER)) {
         // Only the 'center' keyword can be duplicated.
@@ -12274,7 +12279,7 @@ CSSParserImpl::ParsePositionValue(nsCSSValue& aOut)
   for (int32_t i = 0; i < 4; i++) {
     CSSParseResult result =
       ParseVariant(value->Item(i), VARIANT_LPCALC | VARIANT_KEYWORD,
-                   nsCSSProps::kBackgroundPositionKTable);
+                   nsCSSProps::kImageLayerPositionKTable);
     if (result == CSSParseResult::Error) {
       return false;
     } else if (result == CSSParseResult::NotFound) {
@@ -12387,7 +12392,7 @@ CSSParserImpl::ParsePositionValue(nsCSSValue& aOut)
         value->Item(1) = value->Item(0); // move xOffset to correct position
         xEdge.Reset();
       }
-      yEdge.SetIntValue(NS_STYLE_BG_POSITION_CENTER, eCSSUnit_Enumerated);
+      yEdge.SetIntValue(NS_STYLE_IMAGELAYER_POSITION_CENTER, eCSSUnit_Enumerated);
       yOffset.Reset();
       break;
     default:
@@ -12436,13 +12441,13 @@ CSSParserImpl::ParsePositionValue(nsCSSValue& aOut)
 // This function is very similar to ParseScrollSnapCoordinate,
 // ParseBackgroundList, and ParseBackgroundPosition.
 bool
-CSSParserImpl::ParseBackgroundSize()
+CSSParserImpl::ParseImageLayerSize(nsCSSProperty aPropID)
 {
   nsCSSValue value;
   // 'initial', 'inherit' and 'unset' stand alone, no list permitted.
   if (!ParseSingleTokenVariant(value, VARIANT_INHERIT, nullptr)) {
     nsCSSValuePair valuePair;
-    if (!ParseBackgroundSizeValues(valuePair)) {
+    if (!ParseImageLayerSizeValues(valuePair)) {
       return false;
     }
     nsCSSValuePairList* item = value.SetPairListValue();
@@ -12452,14 +12457,14 @@ CSSParserImpl::ParseBackgroundSize()
       if (!ExpectSymbol(',', true)) {
         break;
       }
-      if (!ParseBackgroundSizeValues(valuePair)) {
+      if (!ParseImageLayerSizeValues(valuePair)) {
         return false;
       }
       item->mNext = new nsCSSValuePairList;
       item = item->mNext;
     }
   }
-  AppendValue(eCSSProperty_background_size, value);
+  AppendValue(aPropID, value);
   return true;
 }
 
@@ -12474,7 +12479,7 @@ CSSParserImpl::ParseBackgroundSize()
  * @return Whether or not the operation succeeded.
  */
 #define BG_SIZE_VARIANT (VARIANT_LP | VARIANT_AUTO | VARIANT_CALC)
-bool CSSParserImpl::ParseBackgroundSizeValues(nsCSSValuePair &aOut)
+bool CSSParserImpl::ParseImageLayerSizeValues(nsCSSValuePair &aOut)
 {
   // First try a percentage or a length value
   nsCSSValue &xValue = aOut.mXValue,
@@ -12501,11 +12506,12 @@ bool CSSParserImpl::ParseBackgroundSizeValues(nsCSSValuePair &aOut)
   }
 
   // Now address 'contain' and 'cover'.
-  if (!ParseEnum(xValue, nsCSSProps::kBackgroundSizeKTable))
+  if (!ParseEnum(xValue, nsCSSProps::kImageLayerSizeKTable))
     return false;
   yValue.Reset();
   return true;
 }
+
 #undef BG_SIZE_VARIANT
 
 bool
@@ -16798,8 +16804,7 @@ CSSParserImpl::ParseScrollSnapDestination(nsCSSValue& aValue)
   return true;
 }
 
-// This function is very similar to ParseBackgroundPosition, ParseBackgroundList
-// and ParseBackgroundSize.
+// This function is very similar to ParseImageLayerPosition, and ParseImageLayerSize.
 bool
 CSSParserImpl::ParseScrollSnapCoordinate(nsCSSValue& aValue)
 {
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 926faf3184..345a974d97 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -537,7 +537,7 @@ CSS_PROP_BACKGROUND(
         CSS_PROPERTY_VALUE_LIST_USES_COMMAS,
     "",
     VARIANT_KEYWORD, // used by list parsing
-    kBackgroundAttachmentKTable,
+    kImageLayerAttachmentKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_None)
 CSS_PROP_BACKGROUND(
@@ -550,7 +550,7 @@ CSS_PROP_BACKGROUND(
         CSS_PROPERTY_VALUE_LIST_USES_COMMAS,
     "",
     VARIANT_KEYWORD, // used by list parsing
-    kBackgroundOriginKTable,
+    kImageLayerOriginKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_None)
 CSS_PROP_BACKGROUND(
@@ -605,7 +605,7 @@ CSS_PROP_BACKGROUND(
         CSS_PROPERTY_VALUE_LIST_USES_COMMAS,
     "",
     VARIANT_KEYWORD, // used by list parsing
-    kBackgroundOriginKTable,
+    kImageLayerOriginKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_None)
 CSS_PROP_BACKGROUND(
@@ -620,7 +620,7 @@ CSS_PROP_BACKGROUND(
         CSS_PROPERTY_STORES_CALC,
     "",
     0,
-    kBackgroundPositionKTable,
+    kImageLayerPositionKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Custom)
 CSS_PROP_BACKGROUND(
@@ -633,7 +633,7 @@ CSS_PROP_BACKGROUND(
         CSS_PROPERTY_VALUE_LIST_USES_COMMAS,
     "",
     VARIANT_KEYWORD, // used by list parsing
-    kBackgroundRepeatKTable,
+    kImageLayerRepeatKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_None)
 CSS_PROP_BACKGROUND(
@@ -648,7 +648,7 @@ CSS_PROP_BACKGROUND(
         CSS_PROPERTY_STORES_CALC,
     "",
     0,
-    kBackgroundSizeKTable,
+    kImageLayerSizeKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Custom)
 CSS_PROP_DISPLAY(
@@ -2647,7 +2647,7 @@ CSS_PROP_POSITION(
         CSS_PROPERTY_ENABLED_IN_UA_SHEETS,
     "layout.css.object-fit-and-position.enabled",
     0,
-    kBackgroundPositionKTable,
+    kImageLayerPositionKTable,
     offsetof(nsStylePosition, mObjectPosition),
     eStyleAnimType_Custom)
 CSS_PROP_LOGICAL(
@@ -3128,7 +3128,7 @@ CSS_PROP_DISPLAY(
         CSS_PROPERTY_STORES_CALC,
     "layout.css.scroll-snap.enabled",
     0,
-    kBackgroundPositionKTable,
+    kImageLayerPositionKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_None)
 CSS_PROP_DISPLAY(
@@ -3140,7 +3140,7 @@ CSS_PROP_DISPLAY(
         CSS_PROPERTY_STORES_CALC,
     "layout.css.scroll-snap.enabled",
     0,
-    kBackgroundPositionKTable,
+    kImageLayerPositionKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_None)
 CSS_PROP_DISPLAY(
@@ -3430,7 +3430,7 @@ CSS_PROP_DISPLAY(
         CSS_PROPERTY_GETCS_NEEDS_LAYOUT_FLUSH,
     "",
     0,
-    kBackgroundPositionKTable,
+    kImageLayerPositionKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Custom)
 CSS_PROP_DISPLAY(
@@ -3442,7 +3442,7 @@ CSS_PROP_DISPLAY(
         CSS_PROPERTY_GETCS_NEEDS_LAYOUT_FLUSH,
     "",
     0,
-    kBackgroundPositionKTable,
+    kImageLayerPositionKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Custom)
 CSS_PROP_DISPLAY(
diff --git a/layout/style/nsCSSProps.cpp b/layout/style/nsCSSProps.cpp
index 116351db7a..f307af6dfc 100644
--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -865,57 +865,57 @@ const KTableEntry nsCSSProps::kTransformStyleKTable[] = {
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
-const KTableEntry nsCSSProps::kBackgroundAttachmentKTable[] = {
-  { eCSSKeyword_fixed, NS_STYLE_BG_ATTACHMENT_FIXED },
-  { eCSSKeyword_scroll, NS_STYLE_BG_ATTACHMENT_SCROLL },
-  { eCSSKeyword_local, NS_STYLE_BG_ATTACHMENT_LOCAL },
+const KTableEntry nsCSSProps::kImageLayerAttachmentKTable[] = {
+  { eCSSKeyword_fixed, NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED },
+  { eCSSKeyword_scroll, NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL },
+  { eCSSKeyword_local, NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL },
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
-static_assert(NS_STYLE_BG_CLIP_BORDER == NS_STYLE_BG_ORIGIN_BORDER &&
-              NS_STYLE_BG_CLIP_PADDING == NS_STYLE_BG_ORIGIN_PADDING &&
-              NS_STYLE_BG_CLIP_CONTENT == NS_STYLE_BG_ORIGIN_CONTENT,
+static_assert(NS_STYLE_IMAGELAYER_CLIP_BORDER == NS_STYLE_IMAGELAYER_ORIGIN_BORDER &&
+              NS_STYLE_IMAGELAYER_CLIP_PADDING == NS_STYLE_IMAGELAYER_ORIGIN_PADDING &&
+              NS_STYLE_IMAGELAYER_CLIP_CONTENT == NS_STYLE_IMAGELAYER_ORIGIN_CONTENT,
               "bg-clip and bg-origin style constants must agree");
-const KTableEntry nsCSSProps::kBackgroundOriginKTable[] = {
-  { eCSSKeyword_border_box, NS_STYLE_BG_ORIGIN_BORDER },
-  { eCSSKeyword_padding_box, NS_STYLE_BG_ORIGIN_PADDING },
-  { eCSSKeyword_content_box, NS_STYLE_BG_ORIGIN_CONTENT },
+const KTableEntry nsCSSProps::kImageLayerOriginKTable[] = {
+  { eCSSKeyword_border_box, NS_STYLE_IMAGELAYER_ORIGIN_BORDER },
+  { eCSSKeyword_padding_box, NS_STYLE_IMAGELAYER_ORIGIN_PADDING },
+  { eCSSKeyword_content_box, NS_STYLE_IMAGELAYER_ORIGIN_CONTENT },
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
 // Note: Don't change this table unless you update
-// parseBackgroundPosition!
+// ParseImageLayerPosition!
 
-const KTableEntry nsCSSProps::kBackgroundPositionKTable[] = {
-  { eCSSKeyword_center, NS_STYLE_BG_POSITION_CENTER },
-  { eCSSKeyword_top, NS_STYLE_BG_POSITION_TOP },
-  { eCSSKeyword_bottom, NS_STYLE_BG_POSITION_BOTTOM },
-  { eCSSKeyword_left, NS_STYLE_BG_POSITION_LEFT },
-  { eCSSKeyword_right, NS_STYLE_BG_POSITION_RIGHT },
+const KTableEntry nsCSSProps::kImageLayerPositionKTable[] = {
+  { eCSSKeyword_center, NS_STYLE_IMAGELAYER_POSITION_CENTER },
+  { eCSSKeyword_top, NS_STYLE_IMAGELAYER_POSITION_TOP },
+  { eCSSKeyword_bottom, NS_STYLE_IMAGELAYER_POSITION_BOTTOM },
+  { eCSSKeyword_left, NS_STYLE_IMAGELAYER_POSITION_LEFT },
+  { eCSSKeyword_right, NS_STYLE_IMAGELAYER_POSITION_RIGHT },
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
-const KTableEntry nsCSSProps::kBackgroundRepeatKTable[] = {
-  { eCSSKeyword_no_repeat,  NS_STYLE_BG_REPEAT_NO_REPEAT },
-  { eCSSKeyword_repeat,     NS_STYLE_BG_REPEAT_REPEAT },
-  { eCSSKeyword_repeat_x,   NS_STYLE_BG_REPEAT_REPEAT_X },
-  { eCSSKeyword_repeat_y,   NS_STYLE_BG_REPEAT_REPEAT_Y },
-  { eCSSKeyword_round,      NS_STYLE_BG_REPEAT_ROUND },
-  { eCSSKeyword_space,      NS_STYLE_BG_REPEAT_SPACE },
+const KTableEntry nsCSSProps::kImageLayerRepeatKTable[] = {
+  { eCSSKeyword_no_repeat,  NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT },
+  { eCSSKeyword_repeat,     NS_STYLE_IMAGELAYER_REPEAT_REPEAT },
+  { eCSSKeyword_repeat_x,   NS_STYLE_IMAGELAYER_REPEAT_REPEAT_X },
+  { eCSSKeyword_repeat_y,   NS_STYLE_IMAGELAYER_REPEAT_REPEAT_Y },
+  { eCSSKeyword_round,      NS_STYLE_IMAGELAYER_REPEAT_ROUND },
+  { eCSSKeyword_space,      NS_STYLE_IMAGELAYER_REPEAT_SPACE },
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
-const KTableEntry nsCSSProps::kBackgroundRepeatPartKTable[] = {
-  { eCSSKeyword_no_repeat,  NS_STYLE_BG_REPEAT_NO_REPEAT },
-  { eCSSKeyword_repeat,     NS_STYLE_BG_REPEAT_REPEAT },
-  { eCSSKeyword_round,      NS_STYLE_BG_REPEAT_ROUND },
-  { eCSSKeyword_space,      NS_STYLE_BG_REPEAT_SPACE },
+const KTableEntry nsCSSProps::kImageLayerRepeatPartKTable[] = {
+  { eCSSKeyword_no_repeat,  NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT },
+  { eCSSKeyword_repeat,     NS_STYLE_IMAGELAYER_REPEAT_REPEAT },
+  { eCSSKeyword_round,      NS_STYLE_IMAGELAYER_REPEAT_ROUND },
+  { eCSSKeyword_space,      NS_STYLE_IMAGELAYER_REPEAT_SPACE },
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
-const KTableEntry nsCSSProps::kBackgroundSizeKTable[] = {
-  { eCSSKeyword_contain, NS_STYLE_BG_SIZE_CONTAIN },
-  { eCSSKeyword_cover,   NS_STYLE_BG_SIZE_COVER },
+const KTableEntry nsCSSProps::kImageLayerSizeKTable[] = {
+  { eCSSKeyword_contain, NS_STYLE_IMAGELAYER_SIZE_CONTAIN },
+  { eCSSKeyword_cover,   NS_STYLE_IMAGELAYER_SIZE_COVER },
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
diff --git a/layout/style/nsCSSProps.h b/layout/style/nsCSSProps.h
index 12c58f17aa..55eec06bd2 100644
--- a/layout/style/nsCSSProps.h
+++ b/layout/style/nsCSSProps.h
@@ -670,12 +670,12 @@ public:
   static const KTableEntry kAzimuthKTable[];
   static const KTableEntry kBackfaceVisibilityKTable[];
   static const KTableEntry kTransformStyleKTable[];
-  static const KTableEntry kBackgroundAttachmentKTable[];
-  static const KTableEntry kBackgroundOriginKTable[];
-  static const KTableEntry kBackgroundPositionKTable[];
-  static const KTableEntry kBackgroundRepeatKTable[];
-  static const KTableEntry kBackgroundRepeatPartKTable[];
-  static const KTableEntry kBackgroundSizeKTable[];
+  static const KTableEntry kImageLayerAttachmentKTable[];
+  static const KTableEntry kImageLayerOriginKTable[];
+  static const KTableEntry kImageLayerPositionKTable[];
+  static const KTableEntry kImageLayerRepeatKTable[];
+  static const KTableEntry kImageLayerRepeatPartKTable[];
+  static const KTableEntry kImageLayerSizeKTable[];
   static const KTableEntry kBlendModeKTable[];
   static const KTableEntry kBorderCollapseKTable[];
   static const KTableEntry kBorderColorKTable[];
diff --git a/layout/style/nsCSSValue.cpp b/layout/style/nsCSSValue.cpp
index 7a0524629c..e078cb19ed 100644
--- a/layout/style/nsCSSValue.cpp
+++ b/layout/style/nsCSSValue.cpp
@@ -1517,12 +1517,12 @@ nsCSSValue::AppendToString(nsCSSProperty aProperty, nsAString& aResult,
                    gradient->mBgPos.mYValue.GetUnit() == eCSSUnit_Enumerated,
                    "unexpected unit");
         aResult.AppendLiteral("to");
-        if (!(gradient->mBgPos.mXValue.GetIntValue() & NS_STYLE_BG_POSITION_CENTER)) {
+        if (!(gradient->mBgPos.mXValue.GetIntValue() & NS_STYLE_IMAGELAYER_POSITION_CENTER)) {
           aResult.Append(' ');
           gradient->mBgPos.mXValue.AppendToString(eCSSProperty_background_position,
                                                   aResult, aSerialization);
         }
-        if (!(gradient->mBgPos.mYValue.GetIntValue() & NS_STYLE_BG_POSITION_CENTER)) {
+        if (!(gradient->mBgPos.mYValue.GetIntValue() & NS_STYLE_IMAGELAYER_POSITION_CENTER)) {
           aResult.Append(' ');
           gradient->mBgPos.mYValue.AppendToString(eCSSProperty_background_position,
                                                   aResult, aSerialization);
diff --git a/layout/style/nsComputedDOMStyle.cpp b/layout/style/nsComputedDOMStyle.cpp
index 696b5f2b33..6edfa8b658 100644
--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -1804,17 +1804,16 @@ nsComputedDOMStyle::DoGetFontVariantPosition()
 }
 
 already_AddRefed<CSSValue>
-nsComputedDOMStyle::GetBackgroundList(uint8_t nsStyleBackground::Layer::* aMember,
-                                      uint32_t nsStyleBackground::* aCount,
+nsComputedDOMStyle::GetBackgroundList(uint8_t nsStyleImageLayers::Layer::* aMember,
+                                      uint32_t nsStyleImageLayers::* aCount,
+                                      const nsStyleImageLayers& aLayers,
                                       const KTableEntry aTable[])
 {
-  const nsStyleBackground* bg = StyleBackground();
-
   RefPtr<nsDOMCSSValueList> valueList = GetROCSSValueList(true);
 
-  for (uint32_t i = 0, i_end = bg->*aCount; i < i_end; ++i) {
+  for (uint32_t i = 0, i_end = aLayers.*aCount; i < i_end; ++i) {
     RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-    val->SetIdent(nsCSSProps::ValueToKeywordEnum(bg->mLayers[i].*aMember,
+    val->SetIdent(nsCSSProps::ValueToKeywordEnum(aLayers.mLayers[i].*aMember,
                                                  aTable));
     valueList->AppendCSSValue(val.forget());
   }
@@ -1825,17 +1824,19 @@ nsComputedDOMStyle::GetBackgroundList(uint8_t nsStyleBackground::Layer::* aMembe
 already_AddRefed<CSSValue>
 nsComputedDOMStyle::DoGetBackgroundAttachment()
 {
-  return GetBackgroundList(&nsStyleBackground::Layer::mAttachment,
-                           &nsStyleBackground::mAttachmentCount,
-                           nsCSSProps::kBackgroundAttachmentKTable);
+  return GetBackgroundList(&nsStyleImageLayers::Layer::mAttachment,
+                           &nsStyleImageLayers::mAttachmentCount,
+                           StyleBackground()->mLayers,
+                           nsCSSProps::kImageLayerAttachmentKTable);
 }
 
 already_AddRefed<CSSValue>
 nsComputedDOMStyle::DoGetBackgroundClip()
 {
-  return GetBackgroundList(&nsStyleBackground::Layer::mClip,
-                           &nsStyleBackground::mClipCount,
-                           nsCSSProps::kBackgroundOriginKTable);
+  return GetBackgroundList(&nsStyleImageLayers::Layer::mClip,
+                           &nsStyleImageLayers::mClipCount,
+                           StyleBackground()->mLayers,
+                           nsCSSProps::kImageLayerOriginKTable);
 }
 
 already_AddRefed<CSSValue>
@@ -2137,10 +2138,10 @@ nsComputedDOMStyle::DoGetBackgroundImage()
 
   RefPtr<nsDOMCSSValueList> valueList = GetROCSSValueList(true);
 
-  for (uint32_t i = 0, i_end = bg->mImageCount; i < i_end; ++i) {
+  for (uint32_t i = 0, i_end = bg->mLayers.mImageCount; i < i_end; ++i) {
     RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
 
-    const nsStyleImage& image = bg->mLayers[i].mImage;
+    const nsStyleImage& image = bg->mLayers.mLayers[i].mImage;
     SetValueToStyleImage(image, val);
     valueList->AppendCSSValue(val.forget());
   }
@@ -2151,22 +2152,24 @@ nsComputedDOMStyle::DoGetBackgroundImage()
 already_AddRefed<CSSValue>
 nsComputedDOMStyle::DoGetBackgroundBlendMode()
 {
-  return GetBackgroundList(&nsStyleBackground::Layer::mBlendMode,
-                           &nsStyleBackground::mBlendModeCount,
+  return GetBackgroundList(&nsStyleImageLayers::Layer::mBlendMode,
+                           &nsStyleImageLayers::mBlendModeCount,
+                           StyleBackground()->mLayers,
                            nsCSSProps::kBlendModeKTable);
 }
 
 already_AddRefed<CSSValue>
 nsComputedDOMStyle::DoGetBackgroundOrigin()
 {
-  return GetBackgroundList(&nsStyleBackground::Layer::mOrigin,
-                           &nsStyleBackground::mOriginCount,
-                           nsCSSProps::kBackgroundOriginKTable);
+  return GetBackgroundList(&nsStyleImageLayers::Layer::mOrigin,
+                           &nsStyleImageLayers::mOriginCount,
+                           StyleBackground()->mLayers,
+                           nsCSSProps::kImageLayerOriginKTable);
 }
 
 void
 nsComputedDOMStyle::SetValueToPositionCoord(
-    const nsStyleBackground::Position::PositionCoord& aCoord,
+    const nsStyleImageLayers::Position::PositionCoord& aCoord,
     nsROCSSPrimitiveValue* aValue)
 {
   if (!aCoord.mHasPercent) {
@@ -2182,7 +2185,7 @@ nsComputedDOMStyle::SetValueToPositionCoord(
 
 void
 nsComputedDOMStyle::SetValueToPosition(
-    const nsStyleBackground::Position& aPosition,
+    const nsStyleImageLayers::Position& aPosition,
     nsDOMCSSValueList* aValueList)
 {
   RefPtr<nsROCSSPrimitiveValue> valX = new nsROCSSPrimitiveValue;
@@ -2201,9 +2204,9 @@ nsComputedDOMStyle::DoGetBackgroundPosition()
 
   RefPtr<nsDOMCSSValueList> valueList = GetROCSSValueList(true);
 
-  for (uint32_t i = 0, i_end = bg->mPositionCount; i < i_end; ++i) {
+  for (uint32_t i = 0, i_end = bg->mLayers.mPositionCount; i < i_end; ++i) {
     RefPtr<nsDOMCSSValueList> itemList = GetROCSSValueList(false);
-    SetValueToPosition(bg->mLayers[i].mPosition, itemList);
+    SetValueToPosition(bg->mLayers.mLayers[i].mPosition, itemList);
     valueList->AppendCSSValue(itemList.forget());
   }
 
@@ -2217,23 +2220,23 @@ nsComputedDOMStyle::DoGetBackgroundRepeat()
 
   RefPtr<nsDOMCSSValueList> valueList = GetROCSSValueList(true);
 
-  for (uint32_t i = 0, i_end = bg->mRepeatCount; i < i_end; ++i) {
+  for (uint32_t i = 0, i_end = bg->mLayers.mRepeatCount; i < i_end; ++i) {
     RefPtr<nsDOMCSSValueList> itemList = GetROCSSValueList(false);
     RefPtr<nsROCSSPrimitiveValue> valX = new nsROCSSPrimitiveValue;
 
-    const uint8_t& xRepeat = bg->mLayers[i].mRepeat.mXRepeat;
-    const uint8_t& yRepeat = bg->mLayers[i].mRepeat.mYRepeat;
+    const uint8_t& xRepeat = bg->mLayers.mLayers[i].mRepeat.mXRepeat;
+    const uint8_t& yRepeat = bg->mLayers.mLayers[i].mRepeat.mYRepeat;
 
     bool hasContraction = true;
     unsigned contraction;
     if (xRepeat == yRepeat) {
       contraction = xRepeat;
-    } else if (xRepeat == NS_STYLE_BG_REPEAT_REPEAT &&
-               yRepeat == NS_STYLE_BG_REPEAT_NO_REPEAT) {
-      contraction = NS_STYLE_BG_REPEAT_REPEAT_X;
-    } else if (xRepeat == NS_STYLE_BG_REPEAT_NO_REPEAT &&
-               yRepeat == NS_STYLE_BG_REPEAT_REPEAT) {
-      contraction = NS_STYLE_BG_REPEAT_REPEAT_Y;
+    } else if (xRepeat == NS_STYLE_IMAGELAYER_REPEAT_REPEAT &&
+               yRepeat == NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT) {
+      contraction = NS_STYLE_IMAGELAYER_REPEAT_REPEAT_X;
+    } else if (xRepeat == NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT &&
+               yRepeat == NS_STYLE_IMAGELAYER_REPEAT_REPEAT) {
+      contraction = NS_STYLE_IMAGELAYER_REPEAT_REPEAT_Y;
     } else {
       hasContraction = false;
     }
@@ -2241,14 +2244,14 @@ nsComputedDOMStyle::DoGetBackgroundRepeat()
     RefPtr<nsROCSSPrimitiveValue> valY;
     if (hasContraction) {
       valX->SetIdent(nsCSSProps::ValueToKeywordEnum(contraction,
-                                         nsCSSProps::kBackgroundRepeatKTable));
+                                         nsCSSProps::kImageLayerRepeatKTable));
     } else {
       valY = new nsROCSSPrimitiveValue;
       
       valX->SetIdent(nsCSSProps::ValueToKeywordEnum(xRepeat,
-                                          nsCSSProps::kBackgroundRepeatKTable));
+                                          nsCSSProps::kImageLayerRepeatKTable));
       valY->SetIdent(nsCSSProps::ValueToKeywordEnum(yRepeat,
-                                          nsCSSProps::kBackgroundRepeatKTable));
+                                          nsCSSProps::kImageLayerRepeatKTable));
     }
     itemList->AppendCSSValue(valX.forget());
     if (valY) {
@@ -2267,15 +2270,15 @@ nsComputedDOMStyle::DoGetBackgroundSize()
 
   RefPtr<nsDOMCSSValueList> valueList = GetROCSSValueList(true);
 
-  for (uint32_t i = 0, i_end = bg->mSizeCount; i < i_end; ++i) {
-    const nsStyleBackground::Size &size = bg->mLayers[i].mSize;
+  for (uint32_t i = 0, i_end = bg->mLayers.mSizeCount; i < i_end; ++i) {
+    const nsStyleImageLayers::Size &size = bg->mLayers.mLayers[i].mSize;
 
     switch (size.mWidthType) {
-      case nsStyleBackground::Size::eContain:
-      case nsStyleBackground::Size::eCover: {
+      case nsStyleImageLayers::Size::eContain:
+      case nsStyleImageLayers::Size::eCover: {
         MOZ_ASSERT(size.mWidthType == size.mHeightType,
                    "unsynced types");
-        nsCSSKeyword keyword = size.mWidthType == nsStyleBackground::Size::eContain
+        nsCSSKeyword keyword = size.mWidthType == nsStyleImageLayers::Size::eContain
                              ? eCSSKeyword_contain
                              : eCSSKeyword_cover;
         RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
@@ -2289,11 +2292,11 @@ nsComputedDOMStyle::DoGetBackgroundSize()
         RefPtr<nsROCSSPrimitiveValue> valX = new nsROCSSPrimitiveValue;
         RefPtr<nsROCSSPrimitiveValue> valY = new nsROCSSPrimitiveValue;
 
-        if (size.mWidthType == nsStyleBackground::Size::eAuto) {
+        if (size.mWidthType == nsStyleImageLayers::Size::eAuto) {
           valX->SetIdent(eCSSKeyword_auto);
         } else {
           MOZ_ASSERT(size.mWidthType ==
-                       nsStyleBackground::Size::eLengthPercentage,
+                       nsStyleImageLayers::Size::eLengthPercentage,
                      "bad mWidthType");
           if (!size.mWidth.mHasPercent &&
               // negative values must have come from calc()
@@ -2310,11 +2313,11 @@ nsComputedDOMStyle::DoGetBackgroundSize()
           }
         }
 
-        if (size.mHeightType == nsStyleBackground::Size::eAuto) {
+        if (size.mHeightType == nsStyleImageLayers::Size::eAuto) {
           valY->SetIdent(eCSSKeyword_auto);
         } else {
           MOZ_ASSERT(size.mHeightType ==
-                       nsStyleBackground::Size::eLengthPercentage,
+                       nsStyleImageLayers::Size::eLengthPercentage,
                      "bad mHeightType");
           if (!size.mHeight.mHasPercent &&
               // negative values must have come from calc()
diff --git a/layout/style/nsComputedDOMStyle.h b/layout/style/nsComputedDOMStyle.h
index ea0b97999a..298b4030bc 100644
--- a/layout/style/nsComputedDOMStyle.h
+++ b/layout/style/nsComputedDOMStyle.h
@@ -22,6 +22,7 @@
 #include "nsCoord.h"
 #include "nsColor.h"
 #include "nsIContent.h"
+#include "nsStyleStruct.h"
 
 namespace mozilla {
 namespace dom {
@@ -36,7 +37,6 @@ class nsIPresShell;
 class nsDOMCSSValueList;
 struct nsMargin;
 class nsROCSSPrimitiveValue;
-struct nsStyleBackground;
 class nsStyleCoord;
 class nsStyleCorners;
 struct nsStyleFilter;
@@ -201,8 +201,9 @@ private:
                                                bool aIsBoxShadow);
 
   already_AddRefed<CSSValue> GetBackgroundList(
-    uint8_t nsStyleBackground::Layer::* aMember,
-    uint32_t nsStyleBackground::* aCount,
+    uint8_t nsStyleImageLayers::Layer::* aMember,
+    uint32_t nsStyleImageLayers::* aCount,
+    const nsStyleImageLayers& aLayers,
     const KTableEntry aTable[]);
 
   void GetCSSGradientString(const nsStyleGradient* aGradient,
@@ -555,9 +556,9 @@ private:
   void SetValueToStyleImage(const nsStyleImage& aStyleImage,
                             nsROCSSPrimitiveValue* aValue);
   void SetValueToPositionCoord(
-    const nsStyleBackground::Position::PositionCoord& aCoord,
+    const nsStyleImageLayers::Position::PositionCoord& aCoord,
     nsROCSSPrimitiveValue* aValue);
-  void SetValueToPosition(const nsStyleBackground::Position& aPosition,
+  void SetValueToPosition(const nsStyleImageLayers::Position& aPosition,
                           nsDOMCSSValueList* aValueList);
 
   /**
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index a2c262a61a..69f50e8e81 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -115,7 +115,7 @@ nsConditionalResetStyleData::GetConditionalStyleData(nsStyleStructID aSID,
 static void
   ComputePositionValue(nsStyleContext* aStyleContext,
                        const nsCSSValue& aValue,
-                       nsStyleBackground::Position& aComputedValue,
+                       nsStyleImageLayers::Position& aComputedValue,
                        RuleNodeCacheConditions& aConditions);
 
 /*
@@ -745,15 +745,15 @@ static float
 GetFloatFromBoxPosition(int32_t aEnumValue)
 {
   switch (aEnumValue) {
-  case NS_STYLE_BG_POSITION_LEFT:
-  case NS_STYLE_BG_POSITION_TOP:
+  case NS_STYLE_IMAGELAYER_POSITION_LEFT:
+  case NS_STYLE_IMAGELAYER_POSITION_TOP:
     return 0.0f;
-  case NS_STYLE_BG_POSITION_RIGHT:
-  case NS_STYLE_BG_POSITION_BOTTOM:
+  case NS_STYLE_IMAGELAYER_POSITION_RIGHT:
+  case NS_STYLE_IMAGELAYER_POSITION_BOTTOM:
     return 1.0f;
   default:
     MOZ_FALLTHROUGH_ASSERT("unexpected box position value");
-  case NS_STYLE_BG_POSITION_CENTER:
+  case NS_STYLE_IMAGELAYER_POSITION_CENTER:
     return 0.5f;
   }
 }
@@ -5635,7 +5635,7 @@ nsRuleNode::ComputeDisplayData(void* aStartStruct,
   }
 
   // scroll-snap-coordinate: none, inherit, initial
-  typedef nsStyleBackground::Position Position;
+  typedef nsStyleImageLayers::Position Position;
 
   const nsCSSValue& snapCoordinate = *aRuleData->ValueForScrollSnapCoordinate();
   switch (snapCoordinate.GetUnit()) {
@@ -6383,55 +6383,55 @@ struct BackgroundItemComputer<nsCSSValueList, uint8_t>
 };
 
 template <>
-struct BackgroundItemComputer<nsCSSValuePairList, nsStyleBackground::Repeat>
+struct BackgroundItemComputer<nsCSSValuePairList, nsStyleImageLayers::Repeat>
 {
   static void ComputeValue(nsStyleContext* aStyleContext,
                            const nsCSSValuePairList* aSpecifiedValue,
-                           nsStyleBackground::Repeat& aComputedValue,
+                           nsStyleImageLayers::Repeat& aComputedValue,
                            RuleNodeCacheConditions& aConditions)
   {
     NS_ASSERTION(aSpecifiedValue->mXValue.GetUnit() == eCSSUnit_Enumerated &&
                  (aSpecifiedValue->mYValue.GetUnit() == eCSSUnit_Enumerated ||
                   aSpecifiedValue->mYValue.GetUnit() == eCSSUnit_Null),
                  "Invalid unit");
-    
+
     bool hasContraction = true;
     uint8_t value = aSpecifiedValue->mXValue.GetIntValue();
     switch (value) {
-    case NS_STYLE_BG_REPEAT_REPEAT_X:
-      aComputedValue.mXRepeat = NS_STYLE_BG_REPEAT_REPEAT;
-      aComputedValue.mYRepeat = NS_STYLE_BG_REPEAT_NO_REPEAT;
+    case NS_STYLE_IMAGELAYER_REPEAT_REPEAT_X:
+      aComputedValue.mXRepeat = NS_STYLE_IMAGELAYER_REPEAT_REPEAT;
+      aComputedValue.mYRepeat = NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT;
       break;
-    case NS_STYLE_BG_REPEAT_REPEAT_Y:
-      aComputedValue.mXRepeat = NS_STYLE_BG_REPEAT_NO_REPEAT;
-      aComputedValue.mYRepeat = NS_STYLE_BG_REPEAT_REPEAT;
+    case NS_STYLE_IMAGELAYER_REPEAT_REPEAT_Y:
+      aComputedValue.mXRepeat = NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT;
+      aComputedValue.mYRepeat = NS_STYLE_IMAGELAYER_REPEAT_REPEAT;
       break;
     default:
-      NS_ASSERTION(value == NS_STYLE_BG_REPEAT_NO_REPEAT ||
-                   value == NS_STYLE_BG_REPEAT_REPEAT ||
-                   value == NS_STYLE_BG_REPEAT_SPACE ||
-                   value == NS_STYLE_BG_REPEAT_ROUND, "Unexpected value");
+      NS_ASSERTION(value == NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT ||
+                   value == NS_STYLE_IMAGELAYER_REPEAT_REPEAT ||
+                   value == NS_STYLE_IMAGELAYER_REPEAT_SPACE ||
+                   value == NS_STYLE_IMAGELAYER_REPEAT_ROUND, "Unexpected value");
       aComputedValue.mXRepeat = value;
       hasContraction = false;
       break;
     }
-    
+
     if (hasContraction) {
       NS_ASSERTION(aSpecifiedValue->mYValue.GetUnit() == eCSSUnit_Null,
                    "Invalid unit.");
       return;
     }
-    
+
     switch (aSpecifiedValue->mYValue.GetUnit()) {
     case eCSSUnit_Null:
       aComputedValue.mYRepeat = aComputedValue.mXRepeat;
       break;
     case eCSSUnit_Enumerated:
       value = aSpecifiedValue->mYValue.GetIntValue();
-      NS_ASSERTION(value == NS_STYLE_BG_REPEAT_NO_REPEAT ||
-                   value == NS_STYLE_BG_REPEAT_REPEAT ||
-                   value == NS_STYLE_BG_REPEAT_SPACE ||
-                   value == NS_STYLE_BG_REPEAT_ROUND, "Unexpected value");
+      NS_ASSERTION(value == NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT ||
+                   value == NS_STYLE_IMAGELAYER_REPEAT_REPEAT ||
+                   value == NS_STYLE_IMAGELAYER_REPEAT_SPACE ||
+                   value == NS_STYLE_IMAGELAYER_REPEAT_ROUND, "Unexpected value");
       aComputedValue.mYRepeat = value;
       break;
     default:
@@ -6458,7 +6458,7 @@ struct BackgroundItemComputer<nsCSSValueList, nsStyleImage>
  * This function computes a single PositionCoord from two nsCSSValue objects,
  * which represent an edge and an offset from that edge.
  */
-typedef nsStyleBackground::Position::PositionCoord PositionCoord;
+typedef nsStyleImageLayers::Position::PositionCoord PositionCoord;
 static void
 ComputePositionCoord(nsStyleContext* aStyleContext,
                      const nsCSSValue& aEdge,
@@ -6493,8 +6493,8 @@ ComputePositionCoord(nsStyleContext* aStyleContext,
 
   if (eCSSUnit_Enumerated == aEdge.GetUnit()) {
     int sign;
-    if (aEdge.GetIntValue() & (NS_STYLE_BG_POSITION_BOTTOM |
-                               NS_STYLE_BG_POSITION_RIGHT)) {
+    if (aEdge.GetIntValue() & (NS_STYLE_IMAGELAYER_POSITION_BOTTOM |
+                               NS_STYLE_IMAGELAYER_POSITION_RIGHT)) {
       sign = -1;
     } else {
       sign = 1;
@@ -6513,7 +6513,7 @@ ComputePositionCoord(nsStyleContext* aStyleContext,
 static void
 ComputePositionValue(nsStyleContext* aStyleContext,
                      const nsCSSValue& aValue,
-                     nsStyleBackground::Position& aComputedValue,
+                     nsStyleImageLayers::Position& aComputedValue,
                      RuleNodeCacheConditions& aConditions)
 {
   NS_ASSERTION(aValue.GetUnit() == eCSSUnit_Array,
@@ -6543,11 +6543,11 @@ ComputePositionValue(nsStyleContext* aStyleContext,
 }
 
 template <>
-struct BackgroundItemComputer<nsCSSValueList, nsStyleBackground::Position>
+struct BackgroundItemComputer<nsCSSValueList, nsStyleImageLayers::Position>
 {
   static void ComputeValue(nsStyleContext* aStyleContext,
                            const nsCSSValueList* aSpecifiedValue,
-                           nsStyleBackground::Position& aComputedValue,
+                           nsStyleImageLayers::Position& aComputedValue,
                            RuleNodeCacheConditions& aConditions)
   {
     ComputePositionValue(aStyleContext, aSpecifiedValue->mValue,
@@ -6558,43 +6558,43 @@ struct BackgroundItemComputer<nsCSSValueList, nsStyleBackground::Position>
 
 struct BackgroundSizeAxis {
   nsCSSValue nsCSSValuePairList::* specified;
-  nsStyleBackground::Size::Dimension nsStyleBackground::Size::* result;
-  uint8_t nsStyleBackground::Size::* type;
+  nsStyleImageLayers::Size::Dimension nsStyleImageLayers::Size::* result;
+  uint8_t nsStyleImageLayers::Size::* type;
 };
 
 static const BackgroundSizeAxis gBGSizeAxes[] = {
   { &nsCSSValuePairList::mXValue,
-    &nsStyleBackground::Size::mWidth,
-    &nsStyleBackground::Size::mWidthType },
+    &nsStyleImageLayers::Size::mWidth,
+    &nsStyleImageLayers::Size::mWidthType },
   { &nsCSSValuePairList::mYValue,
-    &nsStyleBackground::Size::mHeight,
-    &nsStyleBackground::Size::mHeightType }
+    &nsStyleImageLayers::Size::mHeight,
+    &nsStyleImageLayers::Size::mHeightType }
 };
 
 template <>
-struct BackgroundItemComputer<nsCSSValuePairList, nsStyleBackground::Size>
+struct BackgroundItemComputer<nsCSSValuePairList, nsStyleImageLayers::Size>
 {
   static void ComputeValue(nsStyleContext* aStyleContext,
                            const nsCSSValuePairList* aSpecifiedValue,
-                           nsStyleBackground::Size& aComputedValue,
+                           nsStyleImageLayers::Size& aComputedValue,
                            RuleNodeCacheConditions& aConditions)
   {
-    nsStyleBackground::Size &size = aComputedValue;
+    nsStyleImageLayers::Size &size = aComputedValue;
     for (const BackgroundSizeAxis *axis = gBGSizeAxes,
                         *axis_end = ArrayEnd(gBGSizeAxes);
          axis < axis_end; ++axis) {
       const nsCSSValue &specified = aSpecifiedValue->*(axis->specified);
       if (eCSSUnit_Auto == specified.GetUnit()) {
-        size.*(axis->type) = nsStyleBackground::Size::eAuto;
+        size.*(axis->type) = nsStyleImageLayers::Size::eAuto;
       }
       else if (eCSSUnit_Enumerated == specified.GetUnit()) {
-        static_assert(nsStyleBackground::Size::eContain ==
-                      NS_STYLE_BG_SIZE_CONTAIN &&
-                      nsStyleBackground::Size::eCover ==
-                      NS_STYLE_BG_SIZE_COVER,
+        static_assert(nsStyleImageLayers::Size::eContain ==
+                      NS_STYLE_IMAGELAYER_SIZE_CONTAIN &&
+                      nsStyleImageLayers::Size::eCover ==
+                      NS_STYLE_IMAGELAYER_SIZE_COVER,
                       "background size constants out of sync");
-        MOZ_ASSERT(specified.GetIntValue() == NS_STYLE_BG_SIZE_CONTAIN ||
-                   specified.GetIntValue() == NS_STYLE_BG_SIZE_COVER,
+        MOZ_ASSERT(specified.GetIntValue() == NS_STYLE_IMAGELAYER_SIZE_CONTAIN ||
+                   specified.GetIntValue() == NS_STYLE_IMAGELAYER_SIZE_COVER,
                    "invalid enumerated value for size coordinate");
         size.*(axis->type) = specified.GetIntValue();
       }
@@ -6610,8 +6610,8 @@ struct BackgroundItemComputer<nsCSSValuePairList, nsStyleBackground::Size>
                      widthValue.GetUnit() != eCSSUnit_Unset,
                      "initial/inherit/unset should already have been handled");
           MOZ_ASSERT(widthValue.GetUnit() == eCSSUnit_Enumerated &&
-                     (widthValue.GetIntValue() == NS_STYLE_BG_SIZE_CONTAIN ||
-                      widthValue.GetIntValue() == NS_STYLE_BG_SIZE_COVER),
+                     (widthValue.GetIntValue() == NS_STYLE_IMAGELAYER_SIZE_CONTAIN ||
+                      widthValue.GetIntValue() == NS_STYLE_IMAGELAYER_SIZE_COVER),
                      "null height value not corresponding to allowable "
                      "non-null width value");
         }
@@ -6622,7 +6622,7 @@ struct BackgroundItemComputer<nsCSSValuePairList, nsStyleBackground::Size>
         (size.*(axis->result)).mLength = 0;
         (size.*(axis->result)).mPercent = specified.GetPercentValue();
         (size.*(axis->result)).mHasPercent = true;
-        size.*(axis->type) = nsStyleBackground::Size::eLengthPercentage;
+        size.*(axis->type) = nsStyleImageLayers::Size::eLengthPercentage;
       }
       else if (specified.IsLengthUnit()) {
         (size.*(axis->result)).mLength =
@@ -6630,7 +6630,7 @@ struct BackgroundItemComputer<nsCSSValuePairList, nsStyleBackground::Size>
                      aConditions);
         (size.*(axis->result)).mPercent = 0.0f;
         (size.*(axis->result)).mHasPercent = false;
-        size.*(axis->type) = nsStyleBackground::Size::eLengthPercentage;
+        size.*(axis->type) = nsStyleImageLayers::Size::eLengthPercentage;
       } else {
         MOZ_ASSERT(specified.IsCalcUnit(), "unexpected unit");
         LengthPercentPairCalcOps ops(aStyleContext,
@@ -6640,16 +6640,16 @@ struct BackgroundItemComputer<nsCSSValuePairList, nsStyleBackground::Size>
         (size.*(axis->result)).mLength = vals.mLength;
         (size.*(axis->result)).mPercent = vals.mPercent;
         (size.*(axis->result)).mHasPercent = ops.mHasPercent;
-        size.*(axis->type) = nsStyleBackground::Size::eLengthPercentage;
+        size.*(axis->type) = nsStyleImageLayers::Size::eLengthPercentage;
       }
     }
 
-    MOZ_ASSERT(size.mWidthType < nsStyleBackground::Size::eDimensionType_COUNT,
+    MOZ_ASSERT(size.mWidthType < nsStyleImageLayers::Size::eDimensionType_COUNT,
                "bad width type");
-    MOZ_ASSERT(size.mHeightType < nsStyleBackground::Size::eDimensionType_COUNT,
+    MOZ_ASSERT(size.mHeightType < nsStyleImageLayers::Size::eDimensionType_COUNT,
                "bad height type");
-    MOZ_ASSERT((size.mWidthType != nsStyleBackground::Size::eContain &&
-                size.mWidthType != nsStyleBackground::Size::eCover) ||
+    MOZ_ASSERT((size.mWidthType != nsStyleImageLayers::Size::eContain &&
+                size.mWidthType != nsStyleImageLayers::Size::eCover) ||
                size.mWidthType == size.mHeightType,
                "contain/cover apply to both dimensions or to neither");
   }
@@ -6657,11 +6657,11 @@ struct BackgroundItemComputer<nsCSSValuePairList, nsStyleBackground::Size>
 
 template <class ComputedValueItem>
 static void
-SetBackgroundList(nsStyleContext* aStyleContext,
+SetImageLayerList(nsStyleContext* aStyleContext,
                   const nsCSSValue& aValue,
-                  nsAutoTArray< nsStyleBackground::Layer, 1> &aLayers,
-                  const nsAutoTArray<nsStyleBackground::Layer, 1> &aParentLayers,
-                  ComputedValueItem nsStyleBackground::Layer::* aResultLocation,
+                  nsAutoTArray< nsStyleImageLayers::Layer, 1> &aLayers,
+                  const nsAutoTArray<nsStyleImageLayers::Layer, 1> &aParentLayers,
+                  ComputedValueItem nsStyleImageLayers::Layer::* aResultLocation,
                   ComputedValueItem aInitialValue,
                   uint32_t aParentItemCount,
                   uint32_t& aItemCount,
@@ -6722,12 +6722,12 @@ SetBackgroundList(nsStyleContext* aStyleContext,
 
 template <class ComputedValueItem>
 static void
-SetBackgroundPairList(nsStyleContext* aStyleContext,
+SetImageLayerPairList(nsStyleContext* aStyleContext,
                       const nsCSSValue& aValue,
-                      nsAutoTArray< nsStyleBackground::Layer, 1> &aLayers,
-                      const nsAutoTArray<nsStyleBackground::Layer, 1>
+                      nsAutoTArray< nsStyleImageLayers::Layer, 1> &aLayers,
+                      const nsAutoTArray<nsStyleImageLayers::Layer, 1>
                                                                  &aParentLayers,
-                      ComputedValueItem nsStyleBackground::Layer::*
+                      ComputedValueItem nsStyleImageLayers::Layer::*
                                                                 aResultLocation,
                       ComputedValueItem aInitialValue,
                       uint32_t aParentItemCount,
@@ -6791,8 +6791,8 @@ SetBackgroundPairList(nsStyleContext* aStyleContext,
 
 template <class ComputedValueItem>
 static void
-FillBackgroundList(nsAutoTArray< nsStyleBackground::Layer, 1> &aLayers,
-    ComputedValueItem nsStyleBackground::Layer::* aResultLocation,
+FillBackgroundList(nsAutoTArray< nsStyleImageLayers::Layer, 1> &aLayers,
+    ComputedValueItem nsStyleImageLayers::Layer::* aResultLocation,
     uint32_t aItemCount, uint32_t aFillCount)
 {
   NS_PRECONDITION(aFillCount <= aLayers.Length(), "unexpected array length");
@@ -6831,101 +6831,100 @@ nsRuleNode::ComputeBackgroundData(void* aStartStruct,
 
   // background-image: url (stored as image), none, inherit [list]
   nsStyleImage initialImage;
-  SetBackgroundList(aContext, *aRuleData->ValueForBackgroundImage(),
-                    bg->mLayers,
-                    parentBG->mLayers, &nsStyleBackground::Layer::mImage,
-                    initialImage, parentBG->mImageCount, bg->mImageCount,
+  SetImageLayerList(aContext, *aRuleData->ValueForBackgroundImage(),
+                    bg->mLayers.mLayers,
+                    parentBG->mLayers.mLayers, &nsStyleImageLayers::Layer::mImage,
+                    initialImage, parentBG->mLayers.mImageCount, bg->mLayers.mImageCount,
                     maxItemCount, rebuild, conditions);
 
   // background-repeat: enum, inherit, initial [pair list]
-  nsStyleBackground::Repeat initialRepeat;
+  nsStyleImageLayers::Repeat initialRepeat;
   initialRepeat.SetInitialValues();
-  SetBackgroundPairList(aContext, *aRuleData->ValueForBackgroundRepeat(),
-                        bg->mLayers,
-                        parentBG->mLayers, &nsStyleBackground::Layer::mRepeat,
-                        initialRepeat, parentBG->mRepeatCount,
-                        bg->mRepeatCount, maxItemCount, rebuild, 
+  SetImageLayerPairList(aContext, *aRuleData->ValueForBackgroundRepeat(),
+                        bg->mLayers.mLayers,
+                        parentBG->mLayers.mLayers, &nsStyleImageLayers::Layer::mRepeat,
+                        initialRepeat, parentBG->mLayers.mRepeatCount,
+                        bg->mLayers.mRepeatCount, maxItemCount, rebuild,
                         conditions);
 
   // background-attachment: enum, inherit, initial [list]
-  SetBackgroundList(aContext, *aRuleData->ValueForBackgroundAttachment(),
-                    bg->mLayers, parentBG->mLayers,
-                    &nsStyleBackground::Layer::mAttachment,
-                    uint8_t(NS_STYLE_BG_ATTACHMENT_SCROLL),
-                    parentBG->mAttachmentCount,
-                    bg->mAttachmentCount, maxItemCount, rebuild,
+  SetImageLayerList(aContext, *aRuleData->ValueForBackgroundAttachment(),
+                    bg->mLayers.mLayers, parentBG->mLayers.mLayers,
+                    &nsStyleImageLayers::Layer::mAttachment,
+                    uint8_t(NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL),
+                    parentBG->mLayers.mAttachmentCount,
+                    bg->mLayers.mAttachmentCount, maxItemCount, rebuild,
                     conditions);
 
   // background-clip: enum, inherit, initial [list]
-  SetBackgroundList(aContext, *aRuleData->ValueForBackgroundClip(),
-                    bg->mLayers,
-                    parentBG->mLayers, &nsStyleBackground::Layer::mClip,
-                    uint8_t(NS_STYLE_BG_CLIP_BORDER), parentBG->mClipCount,
-                    bg->mClipCount, maxItemCount, rebuild, conditions);
+  SetImageLayerList(aContext, *aRuleData->ValueForBackgroundClip(),
+                    bg->mLayers.mLayers,
+                    parentBG->mLayers.mLayers, &nsStyleImageLayers::Layer::mClip,
+                    uint8_t(NS_STYLE_IMAGELAYER_CLIP_BORDER), parentBG->mLayers.mClipCount,
+                    bg->mLayers.mClipCount, maxItemCount, rebuild, conditions);
 
   // background-blend-mode: enum, inherit, initial [list]
-  SetBackgroundList(aContext, *aRuleData->ValueForBackgroundBlendMode(),
-                    bg->mLayers,
-                    parentBG->mLayers, &nsStyleBackground::Layer::mBlendMode,
-                    uint8_t(NS_STYLE_BLEND_NORMAL), parentBG->mBlendModeCount,
-                    bg->mBlendModeCount, maxItemCount, rebuild,
+  SetImageLayerList(aContext, *aRuleData->ValueForBackgroundBlendMode(),
+                    bg->mLayers.mLayers,
+                    parentBG->mLayers.mLayers, &nsStyleImageLayers::Layer::mBlendMode,
+                    uint8_t(NS_STYLE_BLEND_NORMAL), parentBG->mLayers.mBlendModeCount,
+                    bg->mLayers.mBlendModeCount, maxItemCount, rebuild,
                     conditions);
 
   // background-origin: enum, inherit, initial [list]
-  SetBackgroundList(aContext, *aRuleData->ValueForBackgroundOrigin(),
-                    bg->mLayers,
-                    parentBG->mLayers, &nsStyleBackground::Layer::mOrigin,
-                    uint8_t(NS_STYLE_BG_ORIGIN_PADDING), parentBG->mOriginCount,
-                    bg->mOriginCount, maxItemCount, rebuild,
+  SetImageLayerList(aContext, *aRuleData->ValueForBackgroundOrigin(),
+                    bg->mLayers.mLayers,
+                    parentBG->mLayers.mLayers, &nsStyleImageLayers::Layer::mOrigin,
+                    uint8_t(NS_STYLE_IMAGELAYER_ORIGIN_PADDING), parentBG->mLayers.mOriginCount,
+                    bg->mLayers.mOriginCount, maxItemCount, rebuild,
                     conditions);
 
   // background-position: enum, length, percent (flags), inherit [pair list]
-  nsStyleBackground::Position initialPosition;
+  nsStyleImageLayers::Position initialPosition;
   initialPosition.SetInitialPercentValues(0.0f);
-  SetBackgroundList(aContext, *aRuleData->ValueForBackgroundPosition(),
-                    bg->mLayers,
-                    parentBG->mLayers, &nsStyleBackground::Layer::mPosition,
-                    initialPosition, parentBG->mPositionCount,
-                    bg->mPositionCount, maxItemCount, rebuild,
+  SetImageLayerList(aContext, *aRuleData->ValueForBackgroundPosition(),
+                    bg->mLayers.mLayers,
+                    parentBG->mLayers.mLayers, &nsStyleImageLayers::Layer::mPosition,
+                    initialPosition, parentBG->mLayers.mPositionCount,
+                    bg->mLayers.mPositionCount, maxItemCount, rebuild,
                     conditions);
 
   // background-size: enum, length, auto, inherit, initial [pair list]
-  nsStyleBackground::Size initialSize;
+  nsStyleImageLayers::Size initialSize;
   initialSize.SetInitialValues();
-  SetBackgroundPairList(aContext, *aRuleData->ValueForBackgroundSize(),
-                        bg->mLayers,
-                        parentBG->mLayers, &nsStyleBackground::Layer::mSize,
-                        initialSize, parentBG->mSizeCount,
-                        bg->mSizeCount, maxItemCount, rebuild,
+  SetImageLayerPairList(aContext, *aRuleData->ValueForBackgroundSize(),
+                        bg->mLayers.mLayers,
+                        parentBG->mLayers.mLayers, &nsStyleImageLayers::Layer::mSize,
+                        initialSize, parentBG->mLayers.mSizeCount,
+                        bg->mLayers.mSizeCount, maxItemCount, rebuild,
                         conditions);
 
   if (rebuild) {
     // Delete any extra items.  We need to keep layers in which any
     // property was specified.
-    bg->mLayers.TruncateLength(maxItemCount);
+    bg->mLayers.mLayers.TruncateLength(maxItemCount);
 
-    uint32_t fillCount = bg->mImageCount;
-    FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mImage,
-                       bg->mImageCount, fillCount);
-    FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mRepeat,
-                       bg->mRepeatCount, fillCount);
-    FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mAttachment,
-                       bg->mAttachmentCount, fillCount);
-    FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mClip,
-                       bg->mClipCount, fillCount);
-    FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mBlendMode,
-                       bg->mBlendModeCount, fillCount);
-    FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mOrigin,
-                       bg->mOriginCount, fillCount);
-    FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mPosition,
-                       bg->mPositionCount, fillCount);
-    FillBackgroundList(bg->mLayers, &nsStyleBackground::Layer::mSize,
-                       bg->mSizeCount, fillCount);
+    uint32_t fillCount = bg->mLayers.mImageCount;
+    FillBackgroundList(bg->mLayers.mLayers, &nsStyleImageLayers::Layer::mImage,
+                       bg->mLayers.mImageCount, fillCount);
+    FillBackgroundList(bg->mLayers.mLayers, &nsStyleImageLayers::Layer::mRepeat,
+                       bg->mLayers.mRepeatCount, fillCount);
+    FillBackgroundList(bg->mLayers.mLayers, &nsStyleImageLayers::Layer::mAttachment,
+                       bg->mLayers.mAttachmentCount, fillCount);
+    FillBackgroundList(bg->mLayers.mLayers, &nsStyleImageLayers::Layer::mClip,
+                       bg->mLayers.mClipCount, fillCount);
+    FillBackgroundList(bg->mLayers.mLayers, &nsStyleImageLayers::Layer::mBlendMode,
+                       bg->mLayers.mBlendModeCount, fillCount);
+    FillBackgroundList(bg->mLayers.mLayers, &nsStyleImageLayers::Layer::mOrigin,
+                       bg->mLayers.mOriginCount, fillCount);
+    FillBackgroundList(bg->mLayers.mLayers, &nsStyleImageLayers::Layer::mPosition,
+                       bg->mLayers.mPositionCount, fillCount);
+    FillBackgroundList(bg->mLayers.mLayers, &nsStyleImageLayers::Layer::mSize,
+                       bg->mLayers.mSizeCount, fillCount);
   }
 
   // Now that the dust has settled, register the images with the document
-  for (uint32_t i = 0; i < bg->mImageCount; ++i)
-    bg->mLayers[i].TrackImages(aContext->PresContext());
+  bg->mLayers.TrackImages(aContext->PresContext());
 
   COMPUTE_END_RESET(Background, bg)
 }
diff --git a/layout/style/nsStyleConsts.h b/layout/style/nsStyleConsts.h
index 0debf2c743..53f6185c5b 100644
--- a/layout/style/nsStyleConsts.h
+++ b/layout/style/nsStyleConsts.h
@@ -260,55 +260,56 @@ enum class FillMode : uint32_t;
 #define NS_STYLE_ANIMATION_PLAY_STATE_RUNNING     0
 #define NS_STYLE_ANIMATION_PLAY_STATE_PAUSED      1
 
-// See nsStyleBackground
-#define NS_STYLE_BG_ATTACHMENT_SCROLL     0
-#define NS_STYLE_BG_ATTACHMENT_FIXED      1
-#define NS_STYLE_BG_ATTACHMENT_LOCAL      2
+// See nsStyleImageLayers
+#define NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL        0
+#define NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED         1
+#define NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL         2
 
-// See nsStyleBackground
+// See nsStyleImageLayers
 // Code depends on these constants having the same values as BG_ORIGIN_*
-#define NS_STYLE_BG_CLIP_BORDER           0
-#define NS_STYLE_BG_CLIP_PADDING          1
-#define NS_STYLE_BG_CLIP_CONTENT          2
+#define NS_STYLE_IMAGELAYER_CLIP_BORDER              0
+#define NS_STYLE_IMAGELAYER_CLIP_PADDING             1
+#define NS_STYLE_IMAGELAYER_CLIP_CONTENT             2
+
 // A magic value that we use for our "pretend that background-clip is
 // 'padding' when we have a solid border" optimization.  This isn't
-// actually equal to NS_STYLE_BG_CLIP_PADDING because using that
+// actually equal to NS_STYLE_IMAGELAYER_CLIP_PADDING because using that
 // causes antialiasing seams between the background and border.  This
 // is a backend-only value.
-#define NS_STYLE_BG_CLIP_MOZ_ALMOST_PADDING 127
+#define NS_STYLE_IMAGELAYER_CLIP_MOZ_ALMOST_PADDING  127
+
+// See nsStyleImageLayers
+// Code depends on these constants having the same values as BG_CLIP_*
+#define NS_STYLE_IMAGELAYER_ORIGIN_BORDER            0
+#define NS_STYLE_IMAGELAYER_ORIGIN_PADDING           1
+#define NS_STYLE_IMAGELAYER_ORIGIN_CONTENT           2
+
+// See nsStyleImageLayers
+// The parser code depends on |ing these values together.
+#define NS_STYLE_IMAGELAYER_POSITION_CENTER          (1<<0)
+#define NS_STYLE_IMAGELAYER_POSITION_TOP             (1<<1)
+#define NS_STYLE_IMAGELAYER_POSITION_BOTTOM          (1<<2)
+#define NS_STYLE_IMAGELAYER_POSITION_LEFT            (1<<3)
+#define NS_STYLE_IMAGELAYER_POSITION_RIGHT           (1<<4)
+
+// See nsStyleImageLayers
+#define NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT         0x00
+#define NS_STYLE_IMAGELAYER_REPEAT_REPEAT_X          0x01
+#define NS_STYLE_IMAGELAYER_REPEAT_REPEAT_Y          0x02
+#define NS_STYLE_IMAGELAYER_REPEAT_REPEAT            0x03
+#define NS_STYLE_IMAGELAYER_REPEAT_ROUND             0x04
+#define NS_STYLE_IMAGELAYER_REPEAT_SPACE             0x05
+
+
+// See nsStyleImageLayers
+#define NS_STYLE_IMAGELAYER_SIZE_CONTAIN             0
+#define NS_STYLE_IMAGELAYER_SIZE_COVER               1
 
 // See nsStyleBackground
 #define NS_STYLE_BG_INLINE_POLICY_EACH_BOX      0
 #define NS_STYLE_BG_INLINE_POLICY_CONTINUOUS    1
 #define NS_STYLE_BG_INLINE_POLICY_BOUNDING_BOX  2
 
-// See nsStyleBackground
-// Code depends on these constants having the same values as BG_CLIP_*
-#define NS_STYLE_BG_ORIGIN_BORDER         0
-#define NS_STYLE_BG_ORIGIN_PADDING        1
-#define NS_STYLE_BG_ORIGIN_CONTENT        2
-
-// See nsStyleBackground
-// The parser code depends on |ing these values together.
-#define NS_STYLE_BG_POSITION_CENTER  (1<<0)
-#define NS_STYLE_BG_POSITION_TOP     (1<<1)
-#define NS_STYLE_BG_POSITION_BOTTOM  (1<<2)
-#define NS_STYLE_BG_POSITION_LEFT    (1<<3)
-#define NS_STYLE_BG_POSITION_RIGHT   (1<<4)
-
-// See nsStyleBackground
-#define NS_STYLE_BG_REPEAT_NO_REPEAT                0x00
-#define NS_STYLE_BG_REPEAT_REPEAT_X                 0x01
-#define NS_STYLE_BG_REPEAT_REPEAT_Y                 0x02
-#define NS_STYLE_BG_REPEAT_REPEAT                   0x03
-#define NS_STYLE_BG_REPEAT_ROUND                    0x04
-#define NS_STYLE_BG_REPEAT_SPACE                    0x05
-
-
-// See nsStyleBackground
-#define NS_STYLE_BG_SIZE_CONTAIN  0
-#define NS_STYLE_BG_SIZE_COVER    1
-
 // See nsStyleTable
 #define NS_STYLE_BORDER_COLLAPSE                0
 #define NS_STYLE_BORDER_SEPARATE                1
diff --git a/layout/style/nsStyleSet.cpp b/layout/style/nsStyleSet.cpp
index a814916e0b..dc98b52ca6 100644
--- a/layout/style/nsStyleSet.cpp
+++ b/layout/style/nsStyleSet.cpp
@@ -1549,7 +1549,9 @@ nsStyleSet::RuleNodeWithReplacement(Element* aElement,
   // rule tree from ElementRestyler::RestyleSelf to avoid taking that
   // path when we're rebuilding the rule tree.
 
-  nsTArray<RuleNodeInfo> rules;
+  // This array can be hot and often grows to ~20 elements, so inline storage
+  // is best.
+  nsAutoTArray<RuleNodeInfo, 30> rules;
   for (nsRuleNode* ruleNode = aOldRuleNode; !ruleNode->IsRoot();
        ruleNode = ruleNode->GetParent()) {
     RuleNodeInfo* curRule = rules.AppendElement();
diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index 312d478421..ef7b20b256 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -1362,7 +1362,6 @@ bool nsStyleSVGPaint::operator==(const nsStyleSVGPaint& aOther) const
   return true;
 }
 
-
 // --------------------
 // nsStylePosition
 //
@@ -2201,10 +2200,10 @@ nsStyleImage::operator==(const nsStyleImage& aOther) const
 }
 
 // --------------------
-// nsStyleBackground
+// nsStyleImageLayers
 //
 
-nsStyleBackground::nsStyleBackground()
+nsStyleImageLayers::nsStyleImageLayers()
   : mAttachmentCount(1)
   , mClipCount(1)
   , mOriginCount(1)
@@ -2213,15 +2212,13 @@ nsStyleBackground::nsStyleBackground()
   , mImageCount(1)
   , mSizeCount(1)
   , mBlendModeCount(1)
-  , mBackgroundColor(NS_RGBA(0, 0, 0, 0))
 {
-  MOZ_COUNT_CTOR(nsStyleBackground);
-  Layer *onlyLayer = mLayers.AppendElement();
-  NS_ASSERTION(onlyLayer, "auto array must have room for 1 element");
-  onlyLayer->SetInitialValues();
+  MOZ_COUNT_CTOR(nsStyleImageLayers);
+  mLayers.AppendElement();
+  NS_ASSERTION(mLayers.Length() == 1, "auto array must have room for 1 element");
 }
 
-nsStyleBackground::nsStyleBackground(const nsStyleBackground& aSource)
+nsStyleImageLayers::nsStyleImageLayers(const nsStyleImageLayers &aSource)
   : mAttachmentCount(aSource.mAttachmentCount)
   , mClipCount(aSource.mClipCount)
   , mOriginCount(aSource.mOriginCount)
@@ -2231,9 +2228,8 @@ nsStyleBackground::nsStyleBackground(const nsStyleBackground& aSource)
   , mSizeCount(aSource.mSizeCount)
   , mBlendModeCount(aSource.mBlendModeCount)
   , mLayers(aSource.mLayers) // deep copy
-  , mBackgroundColor(aSource.mBackgroundColor)
 {
-  MOZ_COUNT_CTOR(nsStyleBackground);
+  MOZ_COUNT_CTOR(nsStyleImageLayers);
   // If the deep copy of mLayers failed, truncate the counts.
   uint32_t count = mLayers.Length();
   if (count != aSource.mLayers.Length()) {
@@ -2245,94 +2241,12 @@ nsStyleBackground::nsStyleBackground(const nsStyleBackground& aSource)
     mPositionCount = std::max(mPositionCount, count);
     mImageCount = std::max(mImageCount, count);
     mSizeCount = std::max(mSizeCount, count);
-    mBlendModeCount = std::max(mSizeCount, count);
+    mBlendModeCount = std::max(mBlendModeCount, count);
   }
 }
 
-nsStyleBackground::~nsStyleBackground()
-{
-  MOZ_COUNT_DTOR(nsStyleBackground);
-}
-
 void
-nsStyleBackground::Destroy(nsPresContext* aContext)
-{
-  // Untrack all the images stored in our layers
-  for (uint32_t i = 0; i < mImageCount; ++i)
-    mLayers[i].UntrackImages(aContext);
-
-  this->~nsStyleBackground();
-  aContext->PresShell()->
-    FreeByObjectID(eArenaObjectID_nsStyleBackground, this);
-}
-
-nsChangeHint nsStyleBackground::CalcDifference(const nsStyleBackground& aOther) const
-{
-  const nsStyleBackground* moreLayers =
-    mImageCount > aOther.mImageCount ? this : &aOther;
-  const nsStyleBackground* lessLayers =
-    mImageCount > aOther.mImageCount ? &aOther : this;
-
-  nsChangeHint hint = nsChangeHint(0);
-
-  NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT(i, moreLayers) {
-    if (i < lessLayers->mImageCount) {
-      nsChangeHint layerDifference = moreLayers->mLayers[i].CalcDifference(lessLayers->mLayers[i]);
-      hint |= layerDifference;
-      if (layerDifference &&
-          ((moreLayers->mLayers[i].mImage.GetType() == eStyleImageType_Element) ||
-           (lessLayers->mLayers[i].mImage.GetType() == eStyleImageType_Element))) {
-        hint |= nsChangeHint_UpdateEffects | nsChangeHint_RepaintFrame;
-      }
-    } else {
-      hint |= nsChangeHint_RepaintFrame;
-      if (moreLayers->mLayers[i].mImage.GetType() == eStyleImageType_Element) {
-        hint |= nsChangeHint_UpdateEffects | nsChangeHint_RepaintFrame;
-      }
-    }
-  }
-
-  if (mBackgroundColor != aOther.mBackgroundColor) {
-    hint |= nsChangeHint_RepaintFrame;
-  }
-
-  if (hint) {
-    return hint;
-  }
-
-  if (mAttachmentCount != aOther.mAttachmentCount ||
-      mClipCount != aOther.mClipCount ||
-      mOriginCount != aOther.mOriginCount ||
-      mRepeatCount != aOther.mRepeatCount ||
-      mPositionCount != aOther.mPositionCount ||
-      mSizeCount != aOther.mSizeCount) {
-    return nsChangeHint_NeutralChange;
-  }
-
-  return NS_STYLE_HINT_NONE;
-}
-
-bool nsStyleBackground::HasFixedBackground() const
-{
-  NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT(i, this) {
-    const Layer &layer = mLayers[i];
-    if (layer.mAttachment == NS_STYLE_BG_ATTACHMENT_FIXED &&
-        !layer.mImage.IsEmpty()) {
-      return true;
-    }
-  }
-  return false;
-}
-
-bool nsStyleBackground::IsTransparent() const
-{
-  return BottomLayer().mImage.IsEmpty() &&
-         mImageCount == 1 &&
-         NS_GET_A(mBackgroundColor) == 0;
-}
-
-void
-nsStyleBackground::Position::SetInitialPercentValues(float aPercentVal)
+nsStyleImageLayers::Position::SetInitialPercentValues(float aPercentVal)
 {
   mXPosition.mPercent = aPercentVal;
   mXPosition.mLength = 0;
@@ -2343,7 +2257,7 @@ nsStyleBackground::Position::SetInitialPercentValues(float aPercentVal)
 }
 
 void
-nsStyleBackground::Position::SetInitialZeroValues()
+nsStyleImageLayers::Position::SetInitialZeroValues()
 {
   mXPosition.mPercent = 0;
   mXPosition.mLength = 0;
@@ -2354,7 +2268,7 @@ nsStyleBackground::Position::SetInitialZeroValues()
 }
 
 bool
-nsStyleBackground::Size::DependsOnPositioningAreaSize(const nsStyleImage& aImage) const
+nsStyleImageLayers::Size::DependsOnPositioningAreaSize(const nsStyleImage& aImage) const
 {
   MOZ_ASSERT(aImage.GetType() != eStyleImageType_Null,
              "caller should have handled this");
@@ -2433,13 +2347,13 @@ nsStyleBackground::Size::DependsOnPositioningAreaSize(const nsStyleImage& aImage
 }
 
 void
-nsStyleBackground::Size::SetInitialValues()
+nsStyleImageLayers::Size::SetInitialValues()
 {
   mWidthType = mHeightType = eAuto;
 }
 
 bool
-nsStyleBackground::Size::operator==(const Size& aOther) const
+nsStyleImageLayers::Size::operator==(const Size& aOther) const
 {
   MOZ_ASSERT(mWidthType < eDimensionType_COUNT,
              "bad mWidthType for this");
@@ -2457,35 +2371,30 @@ nsStyleBackground::Size::operator==(const Size& aOther) const
 }
 
 void
-nsStyleBackground::Repeat::SetInitialValues() 
+nsStyleImageLayers::Repeat::SetInitialValues()
 {
-  mXRepeat = NS_STYLE_BG_REPEAT_REPEAT;
-  mYRepeat = NS_STYLE_BG_REPEAT_REPEAT;
+  mXRepeat = NS_STYLE_IMAGELAYER_REPEAT_REPEAT;
+  mYRepeat = NS_STYLE_IMAGELAYER_REPEAT_REPEAT;
 }
 
-nsStyleBackground::Layer::Layer()
+nsStyleImageLayers::Layer::Layer()
+: mClip(NS_STYLE_IMAGELAYER_CLIP_BORDER),
+  mOrigin(NS_STYLE_IMAGELAYER_ORIGIN_PADDING),
+  mAttachment(NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL),
+  mBlendMode(NS_STYLE_BLEND_NORMAL)
 {
-}
-
-nsStyleBackground::Layer::~Layer()
-{
-}
-
-void
-nsStyleBackground::Layer::SetInitialValues()
-{
-  mAttachment = NS_STYLE_BG_ATTACHMENT_SCROLL;
-  mClip = NS_STYLE_BG_CLIP_BORDER;
-  mOrigin = NS_STYLE_BG_ORIGIN_PADDING;
-  mRepeat.SetInitialValues();
-  mBlendMode = NS_STYLE_BLEND_NORMAL;
   mPosition.SetInitialPercentValues(0.0f); // Initial value is "0% 0%"
-  mSize.SetInitialValues();
   mImage.SetNull();
+  mRepeat.SetInitialValues();
+  mSize.SetInitialValues();
+}
+
+nsStyleImageLayers::Layer::~Layer()
+{
 }
 
 bool
-nsStyleBackground::Layer::RenderingMightDependOnPositioningAreaSizeChange() const
+nsStyleImageLayers::Layer::RenderingMightDependOnPositioningAreaSizeChange() const
 {
   // Do we even have an image?
   if (mImage.IsEmpty()) {
@@ -2497,7 +2406,7 @@ nsStyleBackground::Layer::RenderingMightDependOnPositioningAreaSizeChange() cons
 }
 
 bool
-nsStyleBackground::Layer::operator==(const Layer& aOther) const
+nsStyleImageLayers::Layer::operator==(const Layer& aOther) const
 {
   return mAttachment == aOther.mAttachment &&
          mClip == aOther.mClip &&
@@ -2510,7 +2419,7 @@ nsStyleBackground::Layer::operator==(const Layer& aOther) const
 }
 
 nsChangeHint
-nsStyleBackground::Layer::CalcDifference(const Layer& aOther) const
+nsStyleImageLayers::Layer::CalcDifference(const nsStyleImageLayers::Layer& aOther) const
 {
   nsChangeHint hint = nsChangeHint(0);
   if (mAttachment != aOther.mAttachment ||
@@ -2528,6 +2437,108 @@ nsStyleBackground::Layer::CalcDifference(const Layer& aOther) const
   return hint;
 }
 
+// --------------------
+// nsStyleBackground
+//
+
+nsStyleBackground::nsStyleBackground()
+  : mBackgroundColor(NS_RGBA(0, 0, 0, 0))
+{
+  MOZ_COUNT_CTOR(nsStyleBackground);
+}
+
+nsStyleBackground::nsStyleBackground(const nsStyleBackground& aSource)
+  : mLayers(aSource.mLayers)
+  , mBackgroundColor(aSource.mBackgroundColor)
+{
+  MOZ_COUNT_CTOR(nsStyleBackground);
+
+}
+
+nsStyleBackground::~nsStyleBackground()
+{
+  MOZ_COUNT_DTOR(nsStyleBackground);
+}
+
+void
+nsStyleBackground::Destroy(nsPresContext* aContext)
+{
+  // Untrack all the images stored in our layers
+  mLayers.UntrackImages(aContext);
+
+  this->~nsStyleBackground();
+  aContext->PresShell()->
+    FreeByObjectID(eArenaObjectID_nsStyleBackground, this);
+}
+
+nsChangeHint nsStyleBackground::CalcDifference(const nsStyleBackground& aOther) const
+{
+  const nsStyleImageLayers& moreLayers =
+    mLayers.mImageCount > aOther.mLayers.mImageCount ?
+      this->mLayers : aOther.mLayers;
+  const nsStyleImageLayers& lessLayers =
+    mLayers.mImageCount > aOther.mLayers.mImageCount ?
+      aOther.mLayers : this->mLayers;
+
+  nsChangeHint hint = nsChangeHint(0);
+
+  NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, moreLayers) {
+    if (i < lessLayers.mImageCount) {
+      nsChangeHint layerDifference = moreLayers.mLayers[i].
+                                       CalcDifference(lessLayers.mLayers[i]);
+      hint |= layerDifference;
+      if (layerDifference &&
+          ((moreLayers.mLayers[i].mImage.GetType() == eStyleImageType_Element) ||
+           (lessLayers.mLayers[i].mImage.GetType() == eStyleImageType_Element))) {
+        hint |= nsChangeHint_UpdateEffects | nsChangeHint_RepaintFrame;
+      }
+    } else {
+      hint |= nsChangeHint_RepaintFrame;
+      if (moreLayers.mLayers[i].mImage.GetType() == eStyleImageType_Element) {
+        hint |= nsChangeHint_UpdateEffects | nsChangeHint_RepaintFrame;
+      }
+    }
+  }
+
+  if (mBackgroundColor != aOther.mBackgroundColor) {
+    hint |= nsChangeHint_RepaintFrame;
+  }
+
+  if (hint) {
+    return hint;
+  }
+
+  if (mLayers.mAttachmentCount != aOther.mLayers.mAttachmentCount ||
+      mLayers.mClipCount != aOther.mLayers.mClipCount ||
+      mLayers.mOriginCount != aOther.mLayers.mOriginCount ||
+      mLayers.mRepeatCount != aOther.mLayers.mRepeatCount ||
+      mLayers.mPositionCount != aOther.mLayers.mPositionCount ||
+      mLayers.mSizeCount != aOther.mLayers.mSizeCount) {
+    return nsChangeHint_NeutralChange;
+  }
+
+  return NS_STYLE_HINT_NONE;
+}
+
+bool nsStyleBackground::HasFixedBackground() const
+{
+  NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, mLayers) {
+    const nsStyleImageLayers::Layer &layer = mLayers.mLayers[i];
+    if (layer.mAttachment == NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED &&
+        !layer.mImage.IsEmpty()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool nsStyleBackground::IsTransparent() const
+{
+  return BottomLayer().mImage.IsEmpty() &&
+         mLayers.mImageCount == 1 &&
+         NS_GET_A(mBackgroundColor) == 0;
+}
+
 // --------------------
 // nsStyleDisplay
 //
diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index 927696e541..82da379592 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -398,29 +398,11 @@ struct nsStyleColor
   nscolor mColor;                 // [inherited]
 };
 
-struct nsStyleBackground
-{
-  nsStyleBackground();
-  nsStyleBackground(const nsStyleBackground& aOther);
-  ~nsStyleBackground();
-
-  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
-    return aContext->PresShell()->
-      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleBackground, sz);
-  }
-  void Destroy(nsPresContext* aContext);
-
-  nsChangeHint CalcDifference(const nsStyleBackground& aOther) const;
-  static nsChangeHint MaxDifference() {
-    return nsChangeHint_UpdateEffects |
-           nsChangeHint_RepaintFrame |
-           nsChangeHint_SchedulePaint |
-           nsChangeHint_NeutralChange;
-  }
-  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
-    // CalcDifference never returns the reflow hints that are sometimes
-    // handled for descendants at all.
-    return nsChangeHint(0);
+struct nsStyleImageLayers {
+  nsStyleImageLayers();
+  nsStyleImageLayers(const nsStyleImageLayers &aSource);
+  ~nsStyleImageLayers() {
+    MOZ_COUNT_DTOR(nsStyleImageLayers);
   }
 
   struct Position;
@@ -536,14 +518,24 @@ struct nsStyleBackground
   struct Layer;
   friend struct Layer;
   struct Layer {
-    uint8_t mAttachment;                // [reset] See nsStyleConsts.h
-    uint8_t mClip;                      // [reset] See nsStyleConsts.h
-    uint8_t mOrigin;                    // [reset] See nsStyleConsts.h
-    uint8_t mBlendMode;                 // [reset] See nsStyleConsts.h
-    Repeat mRepeat;                     // [reset] See nsStyleConsts.h
-    Position mPosition;                 // [reset]
-    nsStyleImage mImage;                // [reset]
-    Size mSize;                         // [reset]
+    nsStyleImage  mImage;         // [reset]
+    Position      mPosition;      // [reset] See nsStyleConsts.h
+    Size          mSize;          // [reset]
+    uint8_t       mClip;          // [reset] See nsStyleConsts.h
+    uint8_t       mOrigin;        // [reset] See nsStyleConsts.h
+    uint8_t       mAttachment;    // [reset] See nsStyleConsts.h
+                                  // background-only property
+                                  // This property is used for background layer
+                                  // only. For a mask layer, it should always
+                                  // be the initial value, which is
+                                  // NS_STYLE_BG_ATTACHMENT_SCROLL.
+    uint8_t       mBlendMode;     // [reset] See nsStyleConsts.h
+                                  // background-only property
+                                  // This property is used for background layer
+                                  // only. For a mask layer, it should always
+                                  // be the initial value, which is
+                                  // NS_STYLE_BLEND_NORMAL.
+    Repeat        mRepeat;        // [reset] See nsStyleConsts.h
 
     // Initializes only mImage
     Layer();
@@ -560,8 +552,6 @@ struct nsStyleBackground
         mImage.UntrackImage(aContext);
     }
 
-    void SetInitialValues();
-
     // True if the rendering of this layer might change when the size
     // of the background positioning area changes.  This is true for any
     // non-solid-color background whose position or size depends on
@@ -590,6 +580,7 @@ struct nsStyleBackground
            mImageCount,
            mSizeCount,
            mBlendModeCount;
+
   // Layers are stored in an array, matching the top-to-bottom order in
   // which they are specified in CSS.  The number of layers to be used
   // should come from the background-image property.  We create
@@ -604,14 +595,46 @@ struct nsStyleBackground
 
   const Layer& BottomLayer() const { return mLayers[mImageCount - 1]; }
 
-  #define NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT(var_, stylebg_) \
-    for (uint32_t var_ = (stylebg_) ? (stylebg_)->mImageCount : 1; var_-- != 0; )
-  #define NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT_WITH_RANGE(var_, stylebg_, start_, count_) \
-    NS_ASSERTION((int32_t)(start_) >= 0 && (uint32_t)(start_) < ((stylebg_) ? (stylebg_)->mImageCount : 1), "Invalid layer start!"); \
+  void TrackImages(nsPresContext* aContext) {
+    for (uint32_t i = 0; i < mImageCount; ++i) {
+        mLayers[i].TrackImages(aContext);
+    }
+  }
+  void UntrackImages(nsPresContext* aContext) {
+    for (uint32_t i = 0; i < mImageCount; ++i)
+      mLayers[i].UntrackImages(aContext);
+  }
+  #define NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(var_, layers_) \
+    for (uint32_t var_ = (layers_).mImageCount; var_-- != 0; )
+  #define NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT_WITH_RANGE(var_, layers_, start_, count_) \
+    NS_ASSERTION((int32_t)(start_) >= 0 && (uint32_t)(start_) < (layers_).mImageCount, "Invalid layer start!"); \
     NS_ASSERTION((count_) > 0 && (count_) <= (start_) + 1, "Invalid layer range!"); \
     for (uint32_t var_ = (start_) + 1; var_-- != (uint32_t)((start_) + 1 - (count_)); )
+};
 
-  nscolor mBackgroundColor;       // [reset]
+struct nsStyleBackground {
+  nsStyleBackground();
+  nsStyleBackground(const nsStyleBackground& aOther);
+  ~nsStyleBackground();
+
+  void* operator new(size_t sz, nsPresContext* aContext) CPP_THROW_NEW {
+    return aContext->PresShell()->
+      AllocateByObjectID(mozilla::eArenaObjectID_nsStyleBackground, sz);
+  }
+  void Destroy(nsPresContext* aContext);
+
+  nsChangeHint CalcDifference(const nsStyleBackground& aOther) const;
+  static nsChangeHint MaxDifference() {
+     return nsChangeHint_UpdateEffects |
+           nsChangeHint_RepaintFrame |
+           nsChangeHint_SchedulePaint |
+           nsChangeHint_NeutralChange;
+  }
+  static nsChangeHint DifferenceAlwaysHandledForDescendants() {
+    // CalcDifference never returns the reflow hints that are sometimes
+    // handled for descendants at all.
+    return nsChangeHint(0);
+  }
 
   // True if this background is completely transparent.
   bool IsTransparent() const;
@@ -621,6 +644,11 @@ struct nsStyleBackground
   // Not inline because it uses an nsCOMPtr<imgIRequest>
   // FIXME: Should be in nsStyleStructInlines.h.
   bool HasFixedBackground() const;
+
+  const nsStyleImageLayers::Layer& BottomLayer() const { return mLayers.BottomLayer(); }
+
+  nsStyleImageLayers mLayers;
+  nscolor mBackgroundColor;       // [reset]
 };
 
 // See https://bugzilla.mozilla.org/show_bug.cgi?id=271586#c43 for why
@@ -1996,10 +2024,10 @@ struct nsStyleDisplay
     return nsChangeHint(0);
   }
 
-  // XXXdholbert, XXXkgilbert nsStyleBackground::Position should probably be
+  // XXXdholbert, XXXkgilbert nsStyleImageLayers::Position should probably be
   // moved to a different scope, since we're now using it in multiple style
   // structs.
-  typedef nsStyleBackground::Position Position;
+  typedef nsStyleImageLayers::Position Position;
 
   // We guarantee that if mBinding is non-null, so are mBinding->GetURI() and
   // mBinding->mOriginPrincipal.
@@ -2380,9 +2408,9 @@ struct nsStylePosition
     return nsChangeHint(0);
   }
 
-  // XXXdholbert nsStyleBackground::Position should probably be moved to a
+  // XXXdholbert nsStyleImageLayers::Position should probably be moved to a
   // different scope, since we're now using it in multiple style structs.
-  typedef nsStyleBackground::Position Position;
+  typedef nsStyleImageLayers::Position Position;
 
   /**
    * Return the computed value for 'align-content'.
@@ -3190,7 +3218,7 @@ public:
     mFillRule = aFillRule;
   }
 
-  typedef nsStyleBackground::Position Position;
+  typedef nsStyleImageLayers::Position Position;
   Position& GetPosition() {
     NS_ASSERTION(mType == eCircle || mType == eEllipse,
                  "expected circle or ellipse");
diff --git a/layout/style/nsStyleUtil.cpp b/layout/style/nsStyleUtil.cpp
index 41aad25964..952c7a79ce 100644
--- a/layout/style/nsStyleUtil.cpp
+++ b/layout/style/nsStyleUtil.cpp
@@ -675,7 +675,7 @@ nsStyleUtil::IsSignificantChild(nsIContent* aChild, bool aTextIsSignificant,
 // For a replaced element whose concrete object size is no larger than the
 // element's content-box, this method checks whether the given
 // "object-position" coordinate might cause overflow in its dimension.
-typedef nsStyleBackground::Position::PositionCoord PositionCoord;
+typedef nsStyleImageLayers::Position::PositionCoord PositionCoord;
 static bool
 ObjectPositionCoordMightCauseOverflow(const PositionCoord& aCoord)
 {
@@ -713,7 +713,7 @@ nsStyleUtil::ObjectPropsMightCauseOverflow(const nsStylePosition* aStylePos)
 
   // Check each of our "object-position" coords to see if it could cause
   // overflow in its dimension:
-  const nsStyleBackground::Position& objectPosistion = aStylePos->mObjectPosition;
+  const nsStyleImageLayers::Position& objectPosistion = aStylePos->mObjectPosition;
   if (ObjectPositionCoordMightCauseOverflow(objectPosistion.mXPosition) ||
       ObjectPositionCoordMightCauseOverflow(objectPosistion.mYPosition)) {
     return true;
diff --git a/layout/svg/SVGTextFrame.cpp b/layout/svg/SVGTextFrame.cpp
index 1f62313dbf..73dd877867 100644
--- a/layout/svg/SVGTextFrame.cpp
+++ b/layout/svg/SVGTextFrame.cpp
@@ -1348,8 +1348,8 @@ struct TextNodeCorrespondence
   uint32_t mUndisplayedCharacters;
 };
 
-NS_DECLARE_FRAME_PROPERTY(TextNodeCorrespondenceProperty,
-                          DeleteValue<TextNodeCorrespondence>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(TextNodeCorrespondenceProperty,
+                                    TextNodeCorrespondence)
 
 /**
  * Returns the number of undisplayed characters before the specified
@@ -5767,7 +5767,7 @@ SetupInheritablePaint(const DrawTarget* aDrawTarget,
                       gfxTextContextPaint* aOuterContextPaint,
                       SVGTextContextPaint::Paint& aTargetPaint,
                       nsStyleSVGPaint nsStyleSVG::*aFillOrStroke,
-                      const FramePropertyDescriptor* aProperty)
+                      nsSVGEffects::ObserverPropertyDescriptor aProperty)
 {
   const nsStyleSVG *style = aFrame->StyleSVG();
   nsSVGPaintServerFrame *ps =
diff --git a/layout/svg/nsSVGEffects.cpp b/layout/svg/nsSVGEffects.cpp
index b47b4f7ce5..90bbc1cdbc 100644
--- a/layout/svg/nsSVGEffects.cpp
+++ b/layout/svg/nsSVGEffects.cpp
@@ -464,7 +464,7 @@ CreatePaintingProperty(nsIURI *aURI, nsIFrame *aFrame, bool aReferenceImage)
 
 static nsSVGRenderingObserver *
 GetEffectProperty(nsIURI *aURI, nsIFrame *aFrame,
-                  const FramePropertyDescriptor *aProperty,
+                  nsSVGEffects::ObserverPropertyDescriptor aProperty,
                   nsSVGRenderingObserver * (* aCreate)(nsIURI *, nsIFrame *, bool))
 {
   if (!aURI)
@@ -491,21 +491,20 @@ GetOrCreateFilterProperty(nsIFrame *aFrame)
     return nullptr;
 
   FrameProperties props = aFrame->Properties();
-  nsSVGFilterProperty *prop =
-    static_cast<nsSVGFilterProperty*>(props.Get(nsSVGEffects::FilterProperty()));
+  nsSVGFilterProperty *prop = props.Get(nsSVGEffects::FilterProperty());
   if (prop)
     return prop;
   prop = new nsSVGFilterProperty(style->mFilters, aFrame);
   if (!prop)
     return nullptr;
   NS_ADDREF(prop);
-  props.Set(nsSVGEffects::FilterProperty(), static_cast<nsISupports*>(prop));
+  props.Set(nsSVGEffects::FilterProperty(), prop);
   return prop;
 }
 
 nsSVGMarkerProperty *
 nsSVGEffects::GetMarkerProperty(nsIURI *aURI, nsIFrame *aFrame,
-                                const FramePropertyDescriptor *aProp)
+                                ObserverPropertyDescriptor aProp)
 {
   MOZ_ASSERT(aFrame->GetType() == nsGkAtoms::svgPathGeometryFrame &&
                static_cast<nsSVGPathGeometryElement*>(aFrame->GetContent())->IsMarkable(),
@@ -516,7 +515,7 @@ nsSVGEffects::GetMarkerProperty(nsIURI *aURI, nsIFrame *aFrame,
 
 nsSVGTextPathProperty *
 nsSVGEffects::GetTextPathProperty(nsIURI *aURI, nsIFrame *aFrame,
-                                  const FramePropertyDescriptor *aProp)
+                                  ObserverPropertyDescriptor aProp)
 {
   return static_cast<nsSVGTextPathProperty*>(
           GetEffectProperty(aURI, aFrame, aProp, CreateTextPathProperty));
@@ -524,7 +523,7 @@ nsSVGEffects::GetTextPathProperty(nsIURI *aURI, nsIFrame *aFrame,
 
 nsSVGPaintingProperty *
 nsSVGEffects::GetPaintingProperty(nsIURI *aURI, nsIFrame *aFrame,
-                                  const FramePropertyDescriptor *aProp)
+                                  ObserverPropertyDescriptor aProp)
 {
   return static_cast<nsSVGPaintingProperty*>(
           GetEffectProperty(aURI, aFrame, aProp, CreatePaintingProperty));
@@ -532,15 +531,14 @@ nsSVGEffects::GetPaintingProperty(nsIURI *aURI, nsIFrame *aFrame,
 
 static nsSVGRenderingObserver *
 GetEffectPropertyForURI(nsIURI *aURI, nsIFrame *aFrame,
-                        const FramePropertyDescriptor *aProperty,
+                        nsSVGEffects::URIObserverHashtablePropertyDescriptor aProperty,
                         nsSVGRenderingObserver * (* aCreate)(nsIURI *, nsIFrame *, bool))
 {
   if (!aURI)
     return nullptr;
 
   FrameProperties props = aFrame->Properties();
-  nsSVGEffects::URIObserverHashtable *hashtable =
-    static_cast<nsSVGEffects::URIObserverHashtable*>(props.Get(aProperty));
+  nsSVGEffects::URIObserverHashtable *hashtable = props.Get(aProperty);
   if (!hashtable) {
     hashtable = new nsSVGEffects::URIObserverHashtable();
     props.Set(aProperty, hashtable);
@@ -557,7 +555,7 @@ GetEffectPropertyForURI(nsIURI *aURI, nsIFrame *aFrame,
 
 nsSVGPaintingProperty *
 nsSVGEffects::GetPaintingPropertyForURI(nsIURI *aURI, nsIFrame *aFrame,
-                                        const FramePropertyDescriptor *aProp)
+                                        URIObserverHashtablePropertyDescriptor aProp)
 {
   return static_cast<nsSVGPaintingProperty*>(
           GetEffectPropertyForURI(aURI, aFrame, aProp, CreatePaintingProperty));
@@ -584,7 +582,7 @@ nsSVGEffects::GetEffectProperties(nsIFrame *aFrame)
 
 nsSVGPaintServerFrame *
 nsSVGEffects::GetPaintServer(nsIFrame *aTargetFrame, const nsStyleSVGPaint *aPaint,
-                             const FramePropertyDescriptor *aType)
+                             ObserverPropertyDescriptor aType)
 {
   if (aPaint->mType != eStyleSVGPaintType_Server)
     return nullptr;
diff --git a/layout/svg/nsSVGEffects.h b/layout/svg/nsSVGEffects.h
index e44a578f91..8752d906b4 100644
--- a/layout/svg/nsSVGEffects.h
+++ b/layout/svg/nsSVGEffects.h
@@ -395,40 +395,43 @@ private:
 class nsSVGEffects {
 public:
   typedef mozilla::dom::Element Element;
-  typedef mozilla::FramePropertyDescriptor FramePropertyDescriptor;
   typedef nsInterfaceHashtable<nsURIHashKey, nsIMutationObserver>
     URIObserverHashtable;
 
-  static void DestroyFilterProperty(void* aPropertyValue)
-  {
-    auto* prop = static_cast<nsSVGFilterProperty*>(aPropertyValue);
+  using ObserverPropertyDescriptor =
+    const mozilla::FramePropertyDescriptor<nsISupports>*;
+  using URIObserverHashtablePropertyDescriptor =
+    const mozilla::FramePropertyDescriptor<URIObserverHashtable>*;
 
+  static void DestroyFilterProperty(nsSVGFilterProperty* aProp)
+  {
     // nsSVGFilterProperty is cycle-collected, so dropping the last reference
     // doesn't necessarily destroy it. We need to tell it that the frame
     // has now become invalid.
-    prop->DetachFromFrame();
+    aProp->DetachFromFrame();
 
-    prop->Release();
+    aProp->Release();
   }
 
-  NS_DECLARE_FRAME_PROPERTY(FilterProperty, DestroyFilterProperty)
-  NS_DECLARE_FRAME_PROPERTY(MaskProperty, ReleaseValue<nsISupports>)
-  NS_DECLARE_FRAME_PROPERTY(ClipPathProperty, ReleaseValue<nsISupports>)
-  NS_DECLARE_FRAME_PROPERTY(MarkerBeginProperty, ReleaseValue<nsISupports>)
-  NS_DECLARE_FRAME_PROPERTY(MarkerMiddleProperty, ReleaseValue<nsISupports>)
-  NS_DECLARE_FRAME_PROPERTY(MarkerEndProperty, ReleaseValue<nsISupports>)
-  NS_DECLARE_FRAME_PROPERTY(FillProperty, ReleaseValue<nsISupports>)
-  NS_DECLARE_FRAME_PROPERTY(StrokeProperty, ReleaseValue<nsISupports>)
-  NS_DECLARE_FRAME_PROPERTY(HrefProperty, ReleaseValue<nsISupports>)
-  NS_DECLARE_FRAME_PROPERTY(BackgroundImageProperty,
-                            DeleteValue<URIObserverHashtable>)
+  NS_DECLARE_FRAME_PROPERTY_WITH_DTOR(FilterProperty, nsSVGFilterProperty,
+                                      DestroyFilterProperty)
+  NS_DECLARE_FRAME_PROPERTY_RELEASABLE(MaskProperty, nsISupports)
+  NS_DECLARE_FRAME_PROPERTY_RELEASABLE(ClipPathProperty, nsISupports)
+  NS_DECLARE_FRAME_PROPERTY_RELEASABLE(MarkerBeginProperty, nsISupports)
+  NS_DECLARE_FRAME_PROPERTY_RELEASABLE(MarkerMiddleProperty, nsISupports)
+  NS_DECLARE_FRAME_PROPERTY_RELEASABLE(MarkerEndProperty, nsISupports)
+  NS_DECLARE_FRAME_PROPERTY_RELEASABLE(FillProperty, nsISupports)
+  NS_DECLARE_FRAME_PROPERTY_RELEASABLE(StrokeProperty, nsISupports)
+  NS_DECLARE_FRAME_PROPERTY_RELEASABLE(HrefProperty, nsISupports)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(BackgroundImageProperty,
+                                      URIObserverHashtable)
 
   /**
    * Get the paint server for a aTargetFrame.
    */
   static nsSVGPaintServerFrame *GetPaintServer(nsIFrame *aTargetFrame,
                                                const nsStyleSVGPaint *aPaint,
-                                               const FramePropertyDescriptor *aProperty);
+                                               ObserverPropertyDescriptor aProperty);
 
   struct EffectProperties {
     nsSVGFilterProperty*   mFilter;
@@ -531,26 +534,26 @@ public:
    */
   static nsSVGMarkerProperty *
   GetMarkerProperty(nsIURI *aURI, nsIFrame *aFrame,
-                    const FramePropertyDescriptor *aProperty);
+                    ObserverPropertyDescriptor aProperty);
   /**
    * Get an nsSVGTextPathProperty for the frame, creating a fresh one if necessary
    */
   static nsSVGTextPathProperty *
   GetTextPathProperty(nsIURI *aURI, nsIFrame *aFrame,
-                      const FramePropertyDescriptor *aProperty);
+                      ObserverPropertyDescriptor aProperty);
   /**
    * Get an nsSVGPaintingProperty for the frame, creating a fresh one if necessary
    */
   static nsSVGPaintingProperty *
   GetPaintingProperty(nsIURI *aURI, nsIFrame *aFrame,
-                      const FramePropertyDescriptor *aProperty);
+                      ObserverPropertyDescriptor aProperty);
   /**
    * Get an nsSVGPaintingProperty for the frame for that URI, creating a fresh
    * one if necessary
    */
   static nsSVGPaintingProperty *
   GetPaintingPropertyForURI(nsIURI *aURI, nsIFrame *aFrame,
-                            const FramePropertyDescriptor *aProp);
+                            URIObserverHashtablePropertyDescriptor aProp);
 };
 
 #endif /*NSSVGEFFECTS_H_*/
diff --git a/layout/svg/nsSVGUtils.h b/layout/svg/nsSVGUtils.h
index d0d64472db..4433c31b41 100644
--- a/layout/svg/nsSVGUtils.h
+++ b/layout/svg/nsSVGUtils.h
@@ -178,7 +178,6 @@ class nsSVGUtils
 {
 public:
   typedef mozilla::dom::Element Element;
-  typedef mozilla::FramePropertyDescriptor FramePropertyDescriptor;
   typedef mozilla::gfx::AntialiasMode AntialiasMode;
   typedef mozilla::gfx::FillRule FillRule;
   typedef mozilla::gfx::GeneralPattern GeneralPattern;
@@ -186,12 +185,7 @@ public:
 
   static void Init();
 
-  static void DestroyObjectBoundingBoxProperty(void* aPropertyValue) {
-    delete static_cast<gfxRect*>(aPropertyValue);
-  }
-
-  NS_DECLARE_FRAME_PROPERTY(ObjectBoundingBoxProperty,
-                            DestroyObjectBoundingBoxProperty);
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(ObjectBoundingBoxProperty, gfxRect)
 
   /**
    * Gets the nearest nsSVGInnerSVGFrame or nsSVGOuterSVGFrame frame. aFrame
diff --git a/layout/tables/nsTableFrame.cpp b/layout/tables/nsTableFrame.cpp
index 6f8e5a074c..18b759f406 100644
--- a/layout/tables/nsTableFrame.cpp
+++ b/layout/tables/nsTableFrame.cpp
@@ -2664,14 +2664,13 @@ nsTableFrame::GetUsedMargin() const
   return nsMargin(0, 0, 0, 0);
 }
 
-NS_DECLARE_FRAME_PROPERTY(TableBCProperty, DeleteValue<BCPropertyData>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(TableBCProperty, BCPropertyData)
 
 BCPropertyData*
 nsTableFrame::GetBCProperty(bool aCreateIfNecessary) const
 {
   FrameProperties props = Properties();
-  BCPropertyData* value = static_cast<BCPropertyData*>
-                          (props.Get(TableBCProperty()));
+  BCPropertyData* value = props.Get(TableBCProperty());
   if (!value && aCreateIfNecessary) {
     value = new BCPropertyData();
     props.Set(TableBCProperty(), value);
@@ -4302,8 +4301,7 @@ BCMapCellInfo::BCMapCellInfo(nsTableFrame* aTableFrame)
   : mTableFrame(aTableFrame)
   , mNumTableRows(aTableFrame->GetRowCount())
   , mNumTableCols(aTableFrame->GetColCount())
-  , mTableBCData(static_cast<BCPropertyData*>(
-      mTableFrame->Properties().Get(TableBCProperty())))
+  , mTableBCData(mTableFrame->Properties().Get(TableBCProperty()))
   , mTableWM(aTableFrame->StyleContext())
 {
   ResetCellInfo();
diff --git a/layout/tables/nsTableFrame.h b/layout/tables/nsTableFrame.h
index 28e3d5787d..b3add27607 100644
--- a/layout/tables/nsTableFrame.h
+++ b/layout/tables/nsTableFrame.h
@@ -134,8 +134,8 @@ public:
   NS_DECL_QUERYFRAME_TARGET(nsTableFrame)
   NS_DECL_FRAMEARENA_HELPERS
 
-  NS_DECLARE_FRAME_PROPERTY(PositionedTablePartArray,
-                            DeleteValue<nsTArray<nsIFrame*>>)
+  NS_DECLARE_FRAME_PROPERTY_DELETABLE(PositionedTablePartArray,
+                                      nsTArray<nsIFrame*>)
 
   /** nsTableOuterFrame has intimate knowledge of the inner table frame */
   friend class nsTableOuterFrame;
diff --git a/layout/tables/nsTablePainter.cpp b/layout/tables/nsTablePainter.cpp
index 0ce897a5d0..1b1ecb9b68 100644
--- a/layout/tables/nsTablePainter.cpp
+++ b/layout/tables/nsTablePainter.cpp
@@ -122,9 +122,9 @@ TableBackgroundPainter::TableBackgroundData::ShouldSetBCBorder() const
     return false;
   }
 
-  const nsStyleBackground *bg = mFrame->StyleBackground();
-  NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT(i, bg) {
-    if (!bg->mLayers[i].mImage.IsEmpty())
+  const nsStyleImageLayers& layers = mFrame->StyleBackground()->mLayers;
+  NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, layers) {
+    if (!layers.mLayers[i].mImage.IsEmpty())
       return true;
   }
   return false;
diff --git a/layout/tables/nsTableRowFrame.cpp b/layout/tables/nsTableRowFrame.cpp
index 914f3f3f22..c159bc9317 100644
--- a/layout/tables/nsTableRowFrame.cpp
+++ b/layout/tables/nsTableRowFrame.cpp
@@ -1418,7 +1418,7 @@ nsTableRowFrame::GetNextRow() const
   return nullptr;
 }
 
-NS_DECLARE_FRAME_PROPERTY(RowUnpaginatedHeightProperty, nullptr)
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(RowUnpaginatedHeightProperty, nscoord)
 
 void
 nsTableRowFrame::SetUnpaginatedBSize(nsPresContext* aPresContext,
@@ -1427,14 +1427,14 @@ nsTableRowFrame::SetUnpaginatedBSize(nsPresContext* aPresContext,
   NS_ASSERTION(!GetPrevInFlow(), "program error");
   // Get the property
   aPresContext->PropertyTable()->
-    Set(this, RowUnpaginatedHeightProperty(), NS_INT32_TO_PTR(aValue));
+    Set(this, RowUnpaginatedHeightProperty(), aValue);
 }
 
 nscoord
 nsTableRowFrame::GetUnpaginatedBSize()
 {
   FrameProperties props = FirstInFlow()->Properties();
-  return NS_PTR_TO_INT32(props.Get(RowUnpaginatedHeightProperty()));
+  return props.Get(RowUnpaginatedHeightProperty());
 }
 
 void nsTableRowFrame::SetContinuousBCBorderWidth(LogicalSide aForSide,
diff --git a/layout/tables/nsTableRowGroupFrame.cpp b/layout/tables/nsTableRowGroupFrame.cpp
index 9580195f06..cb8e1a8e63 100644
--- a/layout/tables/nsTableRowGroupFrame.cpp
+++ b/layout/tables/nsTableRowGroupFrame.cpp
@@ -1858,8 +1858,8 @@ nsTableRowGroupFrame::GetNextSiblingOnLine(nsIFrame*& aFrame,
 
 //end nsLineIterator methods
 
-NS_DECLARE_FRAME_PROPERTY(RowCursorProperty,
-                          DeleteValue<nsTableRowGroupFrame::FrameCursorData>)
+NS_DECLARE_FRAME_PROPERTY_DELETABLE(RowCursorProperty,
+                                    nsTableRowGroupFrame::FrameCursorData)
 
 void
 nsTableRowGroupFrame::ClearRowCursor()
@@ -1905,8 +1905,7 @@ nsTableRowGroupFrame::GetFirstRowContaining(nscoord aY, nscoord* aOverflowAbove)
     return nullptr;
   }
 
-  FrameCursorData* property = static_cast<FrameCursorData*>
-    (Properties().Get(RowCursorProperty()));
+  FrameCursorData* property = Properties().Get(RowCursorProperty());
   uint32_t cursorIndex = property->mCursorIndex;
   uint32_t frameCount = property->mFrames.Length();
   if (cursorIndex >= frameCount)
diff --git a/layout/xul/nsMenuFrame.cpp b/layout/xul/nsMenuFrame.cpp
index 9dcc109dc3..2e08a88a2b 100644
--- a/layout/xul/nsMenuFrame.cpp
+++ b/layout/xul/nsMenuFrame.cpp
@@ -55,12 +55,7 @@ using namespace mozilla;
 #define NSCONTEXTMENUISMOUSEUP 1
 #endif
 
-static void
-AssertNotCalled(void* aPropertyValue)
-{
-  NS_ERROR("popup list should never be destroyed by the FramePropertyTable");
-}
-NS_DECLARE_FRAME_PROPERTY(PopupListProperty, AssertNotCalled)
+NS_DECLARE_FRAME_PROPERTY_FRAMELIST(PopupListProperty)
 
 static int32_t gEatMouseMove = false;
 
@@ -275,8 +270,7 @@ nsMenuFrame::GetPopupList() const
   if (!HasPopup()) {
     return nullptr;
   }
-  nsFrameList* prop =
-    static_cast<nsFrameList*>(Properties().Get(PopupListProperty()));
+  nsFrameList* prop = Properties().Get(PopupListProperty());
   NS_ASSERTION(prop && prop->GetLength() == 1 &&
                prop->FirstChild()->GetType() == nsGkAtoms::menuPopupFrame,
                "popup list should have exactly one nsMenuPopupFrame");
@@ -287,8 +281,7 @@ void
 nsMenuFrame::DestroyPopupList()
 {
   NS_ASSERTION(HasPopup(), "huh?");
-  nsFrameList* prop =
-    static_cast<nsFrameList*>(Properties().Remove(PopupListProperty()));
+  nsFrameList* prop = Properties().Remove(PopupListProperty());
   NS_ASSERTION(prop && prop->IsEmpty(),
                "popup list must exist and be empty when destroying");
   RemoveStateBits(NS_STATE_MENU_HAS_POPUP_LIST);
diff --git a/mfbt/LinkedList.h b/mfbt/LinkedList.h
index 6eb4c63d57..e0f2a03793 100644
--- a/mfbt/LinkedList.h
+++ b/mfbt/LinkedList.h
@@ -325,7 +325,12 @@ public:
     : sentinel(mozilla::Move(aOther.sentinel))
   { }
 
-  ~LinkedList() { MOZ_ASSERT(isEmpty()); }
+  ~LinkedList() {
+    MOZ_ASSERT(isEmpty(),
+               "failing this assertion means this LinkedList's creator is "
+               "buggy: it should have removed all this list's elements before "
+               "the list's destruction");
+  }
 
   /*
    * Add aElem to the front of the list.
diff --git a/mfbt/Poison.cpp b/mfbt/Poison.cpp
index 1e1c3f2d85..b2767011d5 100644
--- a/mfbt/Poison.cpp
+++ b/mfbt/Poison.cpp
@@ -192,9 +192,7 @@ ReservePoisonArea(uintptr_t rgnsize)
     return uintptr_t(result);
   }
 
-  // no usable poison region identified
-  MOZ_CRASH();
-  return 0;
+  MOZ_CRASH("no usable poison region identified");
 }
 
 void
diff --git a/mfbt/XorShift128PlusRNG.h b/mfbt/XorShift128PlusRNG.h
index d38fe117d2..5f8ec70bf8 100644
--- a/mfbt/XorShift128PlusRNG.h
+++ b/mfbt/XorShift128PlusRNG.h
@@ -33,6 +33,11 @@ namespace non_crypto {
  *     Intel(R) Core(TM) i7-4770 CPU @3.40GHz (Haswell). It is the fastest
  *     generator we are aware of with such empirical statistical properties.
  *
+ * The stream of numbers produced by this method repeats every 2**128 - 1 calls
+ * (i.e. never, for all practical purposes). Zero appears 2**64 - 1 times in
+ * this period; all other numbers appear 2**64 times. Additionally, each *bit*
+ * in the produced numbers repeats every 2**128 - 1 calls.
+ *
  * This generator is not suitable as a cryptographically secure random number
  * generator.
  */
@@ -42,14 +47,20 @@ class XorShift128PlusRNG {
  public:
   /*
    * Construct a xorshift128+ pseudo-random number stream using |aInitial0| and
-   * |aInitial1| as the initial state. These may not both be zero; ideally, they
-   * should have an almost even mix of zero and one bits.
+   * |aInitial1| as the initial state.  These MUST NOT both be zero.
+   *
+   * If the initial states contain many zeros, for a few iterations you'll see
+   * many zeroes in the generated numbers.  It's suggested to seed a SplitMix64
+   * generator <http://xorshift.di.unimi.it/splitmix64.c> and use its first two
+   * outputs to seed xorshift128+.
    */
   XorShift128PlusRNG(uint64_t aInitial0, uint64_t aInitial1) {
     setState(aInitial0, aInitial1);
   }
 
-  /* Return a pseudo-random 64-bit number. */
+  /**
+   * Return a pseudo-random 64-bit number.
+   */
   uint64_t next() {
     /*
      * The offsetOfState*() methods below are provided so that exceedingly-rare
@@ -66,9 +77,10 @@ class XorShift128PlusRNG {
   }
 
   /*
-   * Return a pseudo-random floating-point value in the range [0, 1).
-   * More precisely, choose an integer in the range [0, 2**53) and
-   * divide it by 2**53.
+   * Return a pseudo-random floating-point value in the range [0, 1). More
+   * precisely, choose an integer in the range [0, 2**53) and divide it by
+   * 2**53. Given the 2**128 - 1 period noted above, the produced doubles are
+   * all but uniformly distributed in this range.
    */
   double nextDouble() {
     /*
diff --git a/netwerk/base/nsIChannel.idl b/netwerk/base/nsIChannel.idl
index efd32c3525..cb65b10840 100644
--- a/netwerk/base/nsIChannel.idl
+++ b/netwerk/base/nsIChannel.idl
@@ -83,7 +83,16 @@ interface nsIChannel : nsIRequest
     attribute nsIInterfaceRequestor notificationCallbacks;
 
     /**
-     * Transport-level security information (if any) corresponding to the channel.
+     * Transport-level security information (if any) corresponding to the
+     * channel.
+     *
+     * NOTE: In some circumstances TLS information is propagated onto
+     * non-nsIHttpChannel objects to indicate that their contents were likely
+     * delivered over TLS all the same.  For example, document.open() may
+     * create an nsWyciwygChannel to store the data that will be written to the
+     * document.  In that case, if the caller has TLS information, we propagate
+     * that info onto the nsWyciwygChannel given that it is likely that the
+     * caller will be writing data that was delivered over TLS to the document.
      */
     readonly attribute nsISupports securityInfo;
 
diff --git a/toolkit/components/passwordmgr/content/passwordManager.js b/toolkit/components/passwordmgr/content/passwordManager.js
index adb0c66e72..7a2067fbc1 100644
--- a/toolkit/components/passwordmgr/content/passwordManager.js
+++ b/toolkit/components/passwordmgr/content/passwordManager.js
@@ -16,7 +16,7 @@ function SignonsStartup() {
   kSignonBundle = document.getElementById("signonBundle");
   document.getElementById("togglePasswords").label = kSignonBundle.getString("showPasswords");
   document.getElementById("togglePasswords").accessKey = kSignonBundle.getString("showPasswordsAccessKey");
-  document.getElementById("signonsIntro").textContent = kSignonBundle.getString("loginsSpielAll");
+  document.getElementById("signonsIntro").textContent = kSignonBundle.getString("loginsDescriptionAll");
 
   let treecols = document.getElementsByTagName("treecols")[0];
   treecols.addEventListener("click", HandleTreeColumnClick.bind(null, SignonColumnSort));
@@ -75,6 +75,12 @@ var signonsTreeView = {
         return "";
     }
   },
+  isEditable : function(row, col) {
+    if (col.id == "userCol" || col.id == "passwordCol") {
+      return true;
+    }
+    return false;
+  },
   isSeparator : function(index) { return false; },
   isSorted : function() { return false; },
   isContainer : function(index) { return false; },
@@ -86,7 +92,31 @@ var signonsTreeView = {
       return "ltr";
 
     return "";
-  }
+  },
+  setCellText : function(row, col, value) {
+    // If there is a filter, _filterSet needs to be used, otherwise signons is used.
+    let table = signonsTreeView._filterSet.length ? signonsTreeView._filterSet : signons;
+    function _editLogin(field) {
+      if (value == table[row][field]) {
+        return;
+      }
+      let existingLogin = table[row].clone();
+      table[row][field] = value;
+      table[row].timePasswordChanged = Date.now();
+      passwordmanager.modifyLogin(existingLogin, table[row]);
+      signonsTree.treeBoxObject.invalidateRow(row);
+    }
+
+    if (col.id == "userCol") {
+     _editLogin("username");
+
+    } else if (col.id == "passwordCol") {
+      if (!value) {
+        return;
+      }
+      _editLogin("password");
+    }
+  },
 };
 
 
@@ -126,6 +156,8 @@ function SignonSelected() {
   var selections = GetTreeSelections(signonsTree);
   if (selections.length) {
     document.getElementById("removeSignon").removeAttribute("disabled");
+  } else {
+    document.getElementById("removeSignon").setAttribute("disabled", true);
   }
 }
 
@@ -201,11 +233,15 @@ function FinalizeSignonDeletions(syncNeeded) {
 }
 
 function HandleSignonKeyPress(e) {
+  // If editing is currently performed, don't do anything.
+  if (signonsTree.getAttribute("editing")) {
+    return;
+  }
   if (e.keyCode == KeyEvent.DOM_VK_DELETE
 #ifdef XP_MACOSX
       || e.keyCode == KeyEvent.DOM_VK_BACK_SPACE
 #endif
-     ) {
+   ) {
     DeleteSignon();
   }
 }
@@ -274,7 +310,7 @@ function SignonClearFilter() {
   }
   signonsTreeView._lastSelectedRanges = [];
 
-  document.getElementById("signonsIntro").textContent = kSignonBundle.getString("loginsSpielAll");
+  document.getElementById("signonsIntro").textContent = kSignonBundle.getString("loginsDescriptionAll");
 }
 
 function FocusFilterBox() {
@@ -344,7 +380,7 @@ function _filterPasswords()
   if (signonsTreeView.rowCount > 0)
     signonsTreeView.selection.select(0);
 
-  document.getElementById("signonsIntro").textContent = kSignonBundle.getString("loginsSpielFiltered");
+  document.getElementById("signonsIntro").textContent = kSignonBundle.getString("loginsDescriptionFiltered");
 }
 
 function CopyPassword() {
@@ -357,7 +393,7 @@ function CopyPassword() {
                   getService(Components.interfaces.nsIClipboardHelper);
   var row = document.getElementById("signonsTree").currentIndex;
   var password = signonsTreeView.getCellText(row, {id : "passwordCol" });
-  clipboard.copyString(password, document);
+  clipboard.copyString(password);
 }
 
 function CopyUsername() {
@@ -404,3 +440,17 @@ function masterPasswordLogin(noPasswordCallback) {
 
   return token.isLoggedIn();
 }
+
+function escapeKeyHandler() {
+  // If editing is currently performed, don't do anything.
+  if (signonsTree.getAttribute("editing")) {
+    return;
+  }
+  window.close();
+}
+
+function OpenMigrator() {
+  const { MigrationUtils } = Cu.import("resource:///modules/MigrationUtils.jsm", {});
+  // We pass in the type of source we're using for use in telemetry:
+  MigrationUtils.showMigrationWizard(window, [MigrationUtils.MIGRATION_ENTRYPOINT_PASSWORDS]);
+}
diff --git a/toolkit/components/passwordmgr/content/passwordManager.xul b/toolkit/components/passwordmgr/content/passwordManager.xul
index a4ce005950..a13d40aa84 100644
--- a/toolkit/components/passwordmgr/content/passwordManager.xul
+++ b/toolkit/components/passwordmgr/content/passwordManager.xul
@@ -13,7 +13,7 @@
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         onload="Startup(); SignonsStartup();"
         onunload="Shutdown();"
-        title="&savedPasswords.title;"
+        title="&savedLogins.title;"
         persist="width height screenX screenY">
 
   <script type="application/javascript" src="chrome://passwordmgr/content/passwordManagerCommon.js"/>
@@ -24,7 +24,7 @@
 
   <keyset>
     <key keycode="VK_ESCAPE" oncommand="window.close();"/>
-    <key key="&windowClose.key;" modifiers="accel" oncommand="window.close();"/>
+    <key key="&windowClose.key;" modifiers="accel" oncommand="escapeKeyHandler();"/>
     <key key="&focusSearch1.key;" modifiers="accel" oncommand="FocusFilterBox();"/>
     <key key="&focusSearch2.key;" modifiers="accel" oncommand="FocusFilterBox();"/>
   </keyset>
@@ -60,6 +60,7 @@
           style="height: 20em;"
           onkeypress="HandleSignonKeyPress(event)"
           onselect="SignonSelected();"
+          editable="true"
           context="signonsTreeContextMenu">
       <treecols>
         <treecol id="siteCol" label="&treehead.site.label;" flex="40"
@@ -102,6 +103,11 @@
               label="&removeall.label;" accesskey="&removeall.accesskey;"
               oncommand="DeleteAllSignons();"/>
       <spacer flex="1"/>
+#if defined(MOZ_BUILD_APP_IS_BROWSER) && defined(XP_WIN)
+      <button accesskey="&import.accesskey;"
+              label="&import.label;"
+              oncommand="OpenMigrator();"/>
+#endif
       <button id="togglePasswords"
               oncommand="TogglePasswordVisible();"/>
     </hbox>
diff --git a/toolkit/components/passwordmgr/content/passwordManagerExceptions.xul b/toolkit/components/passwordmgr/content/passwordManagerExceptions.xul
index 7268df1f6f..bc75ec9724 100644
--- a/toolkit/components/passwordmgr/content/passwordManagerExceptions.xul
+++ b/toolkit/components/passwordmgr/content/passwordManagerExceptions.xul
@@ -15,7 +15,7 @@
             buttonlabelaccept="&closebutton.label;"
             onload="Startup(); RejectsStartup();"
             onunload="Shutdown();"
-            title="&savedPasswordsExceptions.title;"
+            title="&savedLoginsExceptions.title;"
             persist="width height screenX screenY">
 
   <prefpane id="SignonViewerDialogPane" flex="1">
@@ -23,7 +23,7 @@
     <script type="application/javascript" src="chrome://passwordmgr/content/passwordManagerExceptions.js"/>
 
     <vbox id="rejectedsites" flex="1">
-        <description control="rejectsTree">&loginsSpielExceptions.label;</description>
+        <description control="rejectsTree">&savedLoginsExceptions.desc;</description>
         <separator class="thin"/>
         <tree id="rejectsTree" flex="1" style="height: 10em;" hidecolumnpicker="true"
               onkeypress="HandleRejectKeyPress(event)"
diff --git a/toolkit/components/passwordmgr/moz.build b/toolkit/components/passwordmgr/moz.build
index 2eee1c4281..3d0baad140 100644
--- a/toolkit/components/passwordmgr/moz.build
+++ b/toolkit/components/passwordmgr/moz.build
@@ -4,6 +4,9 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+if CONFIG['MOZ_BUILD_APP'] == 'browser':
+    DEFINES['MOZ_BUILD_APP_IS_BROWSER'] = True
+
 MOCHITEST_MANIFESTS += ['test/mochitest.ini']
 MOCHITEST_CHROME_MANIFESTS += ['test/chrome.ini']
 BROWSER_CHROME_MANIFESTS += ['test/browser/browser.ini']
diff --git a/toolkit/components/passwordmgr/test/browser/browser.ini b/toolkit/components/passwordmgr/test/browser/browser.ini
index 430fc39d38..ffd7d25a17 100644
--- a/toolkit/components/passwordmgr/test/browser/browser.ini
+++ b/toolkit/components/passwordmgr/test/browser/browser.ini
@@ -2,6 +2,7 @@
 support-files =
   authenticate.sjs
 
+[browser_passwordmgr_editing.js]
 [browser_passwordmgr_fields.js]
 [browser_passwordmgr_observers.js]
 [browser_passwordmgr_sort.js]
diff --git a/toolkit/components/passwordmgr/test/browser/browser_passwordmgr_editing.js b/toolkit/components/passwordmgr/test/browser/browser_passwordmgr_editing.js
new file mode 100644
index 0000000000..313152966a
--- /dev/null
+++ b/toolkit/components/passwordmgr/test/browser/browser_passwordmgr_editing.js
@@ -0,0 +1,126 @@
+const { ContentTaskUtils } = Cu.import("resource://testing-common/ContentTaskUtils.jsm", {});
+const TIME_INTERVAL = 500;
+const PWMGR_DLG = "chrome://passwordmgr/content/passwordManager.xul";
+
+let doc;
+let pwmgr;
+let pwmgrdlg;
+let signonsTree;
+
+function addLogin(site, username, password) {
+  let nsLoginInfo = new Components.Constructor("@mozilla.org/login-manager/loginInfo;1",
+                                               Ci.nsILoginInfo, "init");
+  let login = new nsLoginInfo(site, site, null, username, password, "u", "p");
+  Services.logins.addLogin(login);
+}
+
+function getUsername(row) {
+  return signonsTree.view.getCellText(row, signonsTree.columns.getNamedColumn("userCol"));
+}
+
+function getPassword(row) {
+  return signonsTree.view.getCellText(row, signonsTree.columns.getNamedColumn("passwordCol"));
+}
+
+function synthesizeDblClickOnCell(aTree, column, row) {
+  let tbo = aTree.treeBoxObject;
+  let rect = tbo.getCoordsForCellItem(row, aTree.columns[column], "text");
+  let x = rect.x + rect.width / 2;
+  let y = rect.y + rect.height / 2;
+  // Simulate the double click.
+  EventUtils.synthesizeMouse(aTree.body, x, y, { clickCount: 2 },
+                             aTree.ownerDocument.defaultView);
+}
+
+function togglePasswords() {
+  pwmgrdlg.document.querySelector("#togglePasswords").doCommand();
+}
+
+function* editUsernamePromises(site, oldUsername, newUsername) {
+  is(Services.logins.findLogins({}, site, "", "").length, 1, "Correct login found");
+  let login = Services.logins.findLogins({}, site, "", "")[0];
+  is(login.username, oldUsername, "Correct username saved");
+  is(getUsername(0), oldUsername, "Correct username shown");
+  synthesizeDblClickOnCell(signonsTree, 1, 0);
+  yield ContentTaskUtils.waitForCondition(() => signonsTree.getAttribute("editing"),
+                                          "Waiting for editing");
+
+  EventUtils.sendString(newUsername, pwmgrdlg);
+  let signonsIntro = doc.querySelector("#signonsIntro");
+  EventUtils.sendMouseEvent({type: "click"}, signonsIntro, pwmgrdlg);
+  yield ContentTaskUtils.waitForCondition(() => !signonsTree.getAttribute("editing"),
+                                          "Waiting for editing to stop");
+
+  is(Services.logins.findLogins({}, site, "", "").length, 1, "Correct login replaced");
+  login = Services.logins.findLogins({}, site, "", "")[0];
+  is(login.username, newUsername, "Correct username updated");
+  is(getUsername(0), newUsername, "Correct username shown");
+}
+
+function* editPasswordPromises(site, oldPassword, newPassword) {
+  is(Services.logins.findLogins({}, site, "", "").length, 1, "Correct login found");
+  let login = Services.logins.findLogins({}, site, "", "")[0];
+  is(login.password, oldPassword, "Correct password saved");
+  is(getPassword(0), oldPassword, "Correct password shown");
+
+  synthesizeDblClickOnCell(signonsTree, 2, 0);
+  yield ContentTaskUtils.waitForCondition(() => signonsTree.getAttribute("editing"),
+                                          "Waiting for editing");
+
+  EventUtils.sendString(newPassword, pwmgrdlg);
+  let signonsIntro = doc.querySelector("#signonsIntro");
+  EventUtils.sendMouseEvent({type: "click"}, signonsIntro, pwmgrdlg);
+  yield ContentTaskUtils.waitForCondition(() => !signonsTree.getAttribute("editing"),
+                                          "Waiting for editing to stop");
+
+  is(Services.logins.findLogins({}, site, "", "").length, 1, "Correct login replaced");
+  login = Services.logins.findLogins({}, site, "", "")[0];
+  is(login.password, newPassword, "Correct password updated");
+  is(getPassword(0), newPassword, "Correct password shown");
+}
+
+add_task(function* test_setup() {
+  registerCleanupFunction(function() {
+    Services.logins.removeAllLogins();
+  });
+
+  Services.logins.removeAllLogins();
+  // Open the password manager dialog.
+  pwmgrdlg = window.openDialog(PWMGR_DLG, "Toolkit:PasswordManager", "");
+
+  Services.ww.registerNotification(function (aSubject, aTopic, aData) {
+    if (aTopic == "domwindowopened") {
+      let win = aSubject.QueryInterface(Ci.nsIDOMEventTarget);
+      SimpleTest.waitForFocus(function() {
+        EventUtils.sendKey("RETURN", win);
+      }, win);
+    } else if (aSubject.location == pwmgrdlg.location && aTopic == "domwindowclosed") {
+      // Unregister ourself.
+      Services.ww.unregisterNotification(arguments.callee);
+    }
+  });
+
+  yield new Promise((resolve) => {
+    SimpleTest.waitForFocus(() => {
+      doc = pwmgrdlg.document;
+      signonsTree = doc.querySelector("#signonsTree");
+      resolve();
+    }, pwmgrdlg);
+  });
+});
+
+add_task(function* test_edit_multiple_logins() {
+  function* testLoginChange(site, oldUsername, oldPassword, newUsername, newPassword) {
+    addLogin(site, oldUsername, oldPassword);
+    yield* editUsernamePromises(site, oldUsername, newUsername);
+    togglePasswords();
+    yield* editPasswordPromises(site, oldPassword, newPassword);
+    togglePasswords();
+  }
+
+  yield* testLoginChange("http://c.tn/", "userC", "passC", "usernameC", "passwordC");
+  yield* testLoginChange("http://b.tn/", "userB", "passB", "usernameB", "passwordB");
+  yield* testLoginChange("http://a.tn/", "userA", "passA", "usernameA", "passwordA");
+
+  pwmgrdlg.close();
+});
diff --git a/toolkit/components/telemetry/Histograms.json b/toolkit/components/telemetry/Histograms.json
index 52e3473f13..f66d2acb91 100644
--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -4010,6 +4010,43 @@
     "kind": "boolean",
     "description": "THUMBNAILS: Thumbnail found"
   },
+  "FX_MIGRATION_ENTRY_POINT": {
+    "expires_in_version": "49",
+    "kind": "enumerated",
+    "n_values": 10,
+    "releaseChannelCollection": "opt-out",
+    "description": "Where the migration wizard was entered from. 0=Other/catch-all, 1=first-run, 2=refresh-firefox, 3=Places window, 4=Password manager"
+  },
+  "FX_MIGRATION_SOURCE_BROWSER": {
+    "expires_in_version": "49",
+    "kind": "enumerated",
+    "n_values": 15,
+    "releaseChannelCollection": "opt-out",
+    "description": "The browser that data is pulled from. The values correspond to the internal browser ID (see MigrationUtils.jsm)"
+  },
+  "FX_MIGRATION_ERRORS": {
+    "expires_in_version": "49",
+    "kind": "enumerated",
+    "keyed": "true",
+    "n_values": 12,
+    "releaseChannelCollection": "opt-out",
+    "description": "Errors encountered during migration in buckets defined by the datatype, keyed by the string description of the browser."
+  },
+  "FX_MIGRATION_USAGE": {
+    "expires_in_version": "49",
+    "kind": "enumerated",
+    "keyed": "true",
+    "n_values": 12,
+    "releaseChannelCollection": "opt-out",
+    "description": "Usage of migration for each datatype when migration is run through the post-firstrun flow which allows individual datatypes, keyed by the string description of the browser."
+  },
+  "FX_MIGRATION_HOMEPAGE_IMPORTED": {
+    "expires_in_version": "49",
+    "kind": "boolean",
+    "keyed": "true",
+    "releaseChannelCollection": "opt-out",
+    "description": "Whether the homepage was imported during browser migration. Only available on release builds during firstrun."
+  },
   "EVENTLOOP_UI_LAG_EXP_MS": {
     "alert_emails": ["perf-telemetry-alerts@mozilla.com"],
     "expires_in_version": "never",
@@ -8372,6 +8409,11 @@
     "kind": "count",
     "description": "Reports the column that logins are sorted by"
   },
+  "PWMGR_MANAGE_VISIBILITY_TOGGLED": {
+    "expires_in_version": "never",
+    "kind": "boolean",
+    "description": "Whether the visibility of passwords was toggled (0=Hide, 1=Show)"
+  },
   "PWMGR_NUM_PASSWORDS_PER_HOSTNAME": {
     "expires_in_version": "never",
     "kind": "linear",
@@ -8523,6 +8565,11 @@
     "n_buckets": 30,
     "description": "Time PR_Close of a UDP socket taken (ms)"
   },
+  "PERMISSIONS_SQL_CORRUPTED": {
+    "expires_in_version": "never",
+    "kind": "count",
+    "description": "Record the permissions.sqlite init failure"
+  },
   "GRAPHICS_DRIVER_STARTUP_TEST": {
     "alert_emails": ["danderson@mozilla.com"],
     "expires_in_version": "never",
@@ -8707,11 +8754,6 @@
     "releaseChannelCollection": "opt-out",
     "description": "Reports why a graphics sanity test was run. 0=First Run, 1=App Updated, 2=Device Change, 3=Driver Change."
   },
-  "PERMISSIONS_SQL_CORRUPTED": {
-    "expires_in_version": "never",
-    "kind": "count",
-    "description": "Record the permissions.sqlite init failure"
-  },
   "DEFECTIVE_PERMISSIONS_SQL_REMOVED": {
     "expires_in_version": "never",
     "kind": "count",
diff --git a/toolkit/locales/en-US/chrome/passwordmgr/passwordManager.dtd b/toolkit/locales/en-US/chrome/passwordmgr/passwordManager.dtd
index 8a8e08becb..9c59d7edfe 100644
--- a/toolkit/locales/en-US/chrome/passwordmgr/passwordManager.dtd
+++ b/toolkit/locales/en-US/chrome/passwordmgr/passwordManager.dtd
@@ -2,13 +2,13 @@
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
 
-<!ENTITY      savedPasswords.title            "Saved Passwords">
-<!ENTITY      savedPasswordsExceptions.title  "Exceptions - Saved Passwords">
+<!ENTITY      savedLogins.title               "Saved Logins">
+<!ENTITY      savedLoginsExceptions.title     "Exceptions - Saved Logins">
+<!ENTITY      savedLoginsExceptions.desc      "Logins for the following sites will not be saved:">
+
 <!ENTITY      closebutton.label               "Close">
 <!ENTITY      closebutton.accesskey           "C">
 
-<!ENTITY      loginsSpielExceptions.label     "Passwords for the following sites will not be saved:">
-
 <!ENTITY      treehead.site.label             "Site">
 <!ENTITY      treehead.username.label         "Username">
 <!ENTITY      treehead.password.label         "Password">
@@ -22,6 +22,9 @@
 <!ENTITY      removeall.label                 "Remove All">
 <!ENTITY      removeall.accesskey             "A">
 
+<!ENTITY      import.label                    "Import¡K">
+<!ENTITY      import.accesskey                "I">
+
 <!ENTITY      filter.label                    "Search:">
 <!ENTITY      filter.accesskey                "S">
 
diff --git a/toolkit/locales/en-US/chrome/passwordmgr/passwordmgr.properties b/toolkit/locales/en-US/chrome/passwordmgr/passwordmgr.properties
index db1bdc0c3b..481fa4b082 100644
--- a/toolkit/locales/en-US/chrome/passwordmgr/passwordmgr.properties
+++ b/toolkit/locales/en-US/chrome/passwordmgr/passwordmgr.properties
@@ -38,5 +38,3 @@ showPasswordsAccessKey=P
 noMasterPasswordPrompt=Are you sure you wish to show your passwords?
 removeAllPasswordsPrompt=Are you sure you wish to remove all passwords?
 removeAllPasswordsTitle=Remove all passwords
-loginsSpielAll=Passwords for the following sites are stored on your computer:
-loginsSpielFiltered=The following passwords match your search:
diff --git a/widget/TextEvents.h b/widget/TextEvents.h
index 4202bceb1f..6216e391cb 100644
--- a/widget/TextEvents.h
+++ b/widget/TextEvents.h
@@ -595,7 +595,8 @@ public:
     uint32_t mOffset;
     uint32_t mLength;
   } mInput;
-  struct
+
+  struct Reply
   {
     void* mContentsRoot;
     uint32_t mOffset;
@@ -611,18 +612,29 @@ public:
     mozilla::LayoutDeviceIntRect mRect;
     // The return widget has the caret. This is set at all query events.
     nsIWidget* mFocusedWidget;
-    // true if selection is reversed (end < start)
-    bool mReversed;
-    // true if the selection exists
-    bool mHasSelection;
-    // true if DOM element under mouse belongs to widget
-    bool mWidgetIsHit;
     // mozilla::WritingMode value at the end (focus) of the selection
     mozilla::WritingMode mWritingMode;
     // Used by eQuerySelectionAsTransferable
     nsCOMPtr<nsITransferable> mTransferable;
     // Used by eQueryTextContent with font ranges requested
     nsAutoTArray<mozilla::FontRange, 1> mFontRanges;
+    // true if selection is reversed (end < start)
+    bool mReversed;
+    // true if the selection exists
+    bool mHasSelection;
+    // true if DOM element under mouse belongs to widget
+    bool mWidgetIsHit;
+
+    Reply()
+      : mContentsRoot(nullptr)
+      , mOffset(NOT_FOUND)
+      , mTentativeCaretOffset(NOT_FOUND)
+      , mFocusedWidget(nullptr)
+      , mReversed(false)
+      , mHasSelection(false)
+      , mWidgetIsHit(false)
+    {
+    }
   } mReply;
 
   enum