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.

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;
     }