import changes from `dev' branch of rmottola/Arctic-Fox:

- Bug 1209252: add buttons to clear session and signaling logs. r=jib, r=sicking (39d0a4b57d)
- Bug 1197673 - Use float type for SetAudioOutputVolume. r=eitan (75eae2f441)
- Bug 1188099 - (Part 4) Introduce mochitest coverage for speech global queue. r=smaug r=kdavis (fd4c804c72)
- Bug 1226015 - Have child send __delete__ in speech synth request protocol, fixes race. r=smaug (c46532745a)
- Bug 1230533 - Cancel speech when controlling window goes away. r=smaug (3dae89ffaf)
- Bug 1237176 - skip dom/media/webspeech/synth/test/test_bfcache.html on Linux and Android for frequent timeouts (0d1eabb6fb)
- Bug 1237176 - actually disable test_bfcache.html on Android (1558e0bf39)
- Bug 1240871 - Don't allow implicit "async" in IPDL (r=mccr8,billm) (1db25ace3c)
- Bug 1000040 - Part 2: Implement EthernetManager; r=vicamo (82c01ca9a7)
- Bug 1000040 - Part 3: Test cases; r=vicamo (6a967cc5d9)
- Bug 1245241 - part 2 - remove TYPE_SYSV Shmems from IPDL. r=billm (6d6a4570ca)
- Bug 1245241 - part 3 - remove unused AdoptShmem from IPDL. r=billm (2762a13841)
- Bug 1107792: Don't ask for similar if the surface has an error, and more data in crash reports. r=milan (ead5108a93)
- Bug 1231881 - Remove NativeSurfaceType::CAIRO_SURFACE. r=bas. (c0f03e02f6)
- Bug 1241163 - Replace DrawTarget::CreateSourceSurfaceFromNativeSurface(CAIRO_CONTEXT) with Factory::CreateSourceSurfaceForCairoSurface. r=jrmuizel (06a96cdce6)
- Bug 1240177 - part 1 - add helper function to make Skia image info, r=jrmuizel (6a7d05aeb7)
- Bug 1240177 - part 2 - cleanups of DrawTargetSkia and SourceSurfaceSkia creation for GPU contexts, r=jrmuizel (3211ea9c0e)
- Bug 1240177 - part 3 - make DrawTargetSkia::OptimizeSourceSurface directly upload to GPU textures, r=jrmuizel (743d57a46c)
- Bug 1240177 - part 4 - avoid GPU readbacks in SourceSurfaceSkia::DrawTargetWillChange, r=jrmuizel (f568754717)
- Bug 1240177 - fix SourceSurfaceSkia::DrawTargetWillChange deepCopyTo usage. r=mattwoodrow (2e53d13ba3)
- Bug 1239152 Memset RGBX surfaces to opaque white. r=nical (977c7d5ede)
- Bug 1245241 - part 4 - move SharedMemorySysV details into nsShmImage. r=nical (0015d3caac)
- Bug 1245241 - Force the main thread to sync with the compositor when it tries to allocate insane amounts of shmems. r=lsalzman (7683d2afa7)
- Bug 1245241 - fix SharedMemoryBasic_android CloseHandle to null out handle. r=billm a=kwierso (9fa3f93233)
- Bug 1239152 - skip memset since XShm is already initialized to zero. r=mchang (477ecf2d9a)
- Bug 1227927 Part 1 - Make nsIFrame::PrincipalChildList a const function. r=bz (d9b690a1bc)
- Bug 1214377 - Hack to solve Thunderbird's need to detect style pre-wrap. r=roc a=me (a481ba9020)
- Bug 1214377 - Hack to solve Thunderbird's need to detect style pre-wrap. rs=ehsan on a CLOSED TREE (a15dfcaeb3)
- Bug 1240372 - Don't OOM crash in nsDocumentEncoder::EncodeToStringWithMaxLength() when the string buffer allocation fails; r=bzbarsky (76bed6a40a)
- Bug 1143570 - Part 1: Use an nsBlockInFlowLineIterator to determine whether a BR frame is visible or not; r=roc (99609f6fcd)
- Bug 1064843 part 2 - Make nsSubDocumentFrame inherit nsContainerFrame. r=dholbert (070202e396)
- Bug 1064843 part 3 - Make nsFormControlFrame inherit nsContainerFrame. r=dholbert (cee5125993)
- Bug 1064843 part 4 - Add a placeholder type for top layer. r=roc (e4e564b05b)
- Bug 1064843 part 5 - Ensure frames behave properly for unknown child list id passed into SetInitialChildList. r=dholbert (540f3da6a1)
- Bug 1064843 part 6 - Add backdrop frame list. r=dholbert (79f91fc815)
- Bug 1215365 - Update ua style sheet of fullscreen element. r=heycam (b44060a518)
- Bug 1235969 - Unprefix uses of -moz-transform, -moz-transform-origin and -moz-backface-visibility in UA style sheets. r=xidorn (c7a83cdcae)
- Bug 1064843 part 7 - Add backdrop pseudo-element and add related UA stylesheet. r=heycam (1d89afa54a)
- Bug 1064843 part 8 - Add frame class for backdrop frame. r=dbaron (9146be0073)
- Bug 1064843 part 9 - Change nsCSSFrameConstructor::CreatePlaceholderFrameFor to accept parent style context. r=dbaron (bc860e67f8)
- Bug 1064843 part 10 - Create and render backdrop frame for top layer frames. r=dbaron (1c6f165769)
- Bug 1064843 part 11 - Move checkWindowPureColor helper function from top-layer test to WindowSnapshot.js. r=roc (ef274dec50)
- Bug 1064843 part 12 - Add test for ::backdrop of fullscreen. r=dholbert (b978209868)
- Bug 1227927 Part 2 - Remove nsIFrame::GetFirstPrincipalChild(). r=mats (3f4ba2ef58)
- Bug 1227927 Part 3 - Use ranged-based for-loop to rewrite some simple loops in part 2. r=mats (6b22236653)
- Bug 1227927 Part 4 - Add comment to nsFrameList::GetLength() to warn it's O(n). r=mats (a08aa9185e)
- Bug 1101817 - Part 1: Remove usages of WeakMap.prototype.clear from Gecko. r=yzen,mak,yoric,gijs,jlongster (a992931bfe)
- Bug 1101817 - Part 3: Remove WeakMap.prototype.clear usages from Addons SDK. r=mossop (e81a8c3477)
- Bug 1101817 - Part 4: Remove WeakMap.prototype.clear from web-platform test. r=Ms2ger (1be3f645a2)
- Bug 1101817 - Part 6: Remove Weak{Map,Set}.prototype.clear. r=evilpie (7a0dbffdc9)
- Bug 1235152 - [css-break] Don't apply border/padding twice on inlines with box-decoration-break:clone and direction:rtl. r=roc (e6446262c1)

dom/base/nsDocumentEncoder.cpp

@@ -49,6 +49,8 @@
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/ShadowRoot.h"
 #include "mozilla/dom/EncodingUtils.h"
+#include "nsContainerFrame.h"
+#include "nsBlockFrame.h"
 #include "nsComputedDOMStyle.h"
 
 using namespace mozilla;
@@ -324,7 +326,43 @@ nsDocumentEncoder::IncludeInContext(nsINode *aNode)
 
 static
 bool
-IsInvisibleBreak(nsINode *aNode) {
+LineHasNonEmptyContentWorker(nsIFrame* aFrame)
+{
+  // Look for non-empty frames, but ignore inline and br frames.
+  // For inline frames, descend into the children, if any.
+  if (aFrame->GetType() == nsGkAtoms::inlineFrame) {
+    for (nsIFrame* child : aFrame->PrincipalChildList()) {
+      if (LineHasNonEmptyContentWorker(child)) {
+        return true;
+      }
+    }
+  } else {
+    if (aFrame->GetType() != nsGkAtoms::brFrame &&
+        !aFrame->IsEmpty()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+static
+bool
+LineHasNonEmptyContent(nsLineBox* aLine)
+{
+  int32_t count = aLine->GetChildCount();
+  for (nsIFrame* frame = aLine->mFirstChild; count > 0;
+       --count, frame = frame->GetNextSibling()) {
+    if (LineHasNonEmptyContentWorker(frame)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+static
+bool
+IsInvisibleBreak(nsINode *aNode)
+{
   if (!aNode->IsElement() || !aNode->IsEditable()) {
     return false;
   }
@@ -333,14 +371,36 @@ IsInvisibleBreak(nsINode *aNode) {
     return false;
   }
 
-  // If the BRFrame has caused a visible line break, it should have a next
-  // sibling, or otherwise no siblings (or immediately after a br) and a
-  // non-zero height.
-  bool visible = frame->GetNextSibling() ||
-                 ((!frame->GetPrevSibling() ||
-                   frame->GetPrevSibling()->GetType() == nsGkAtoms::brFrame) &&
-                  frame->GetRect().Height() != 0);
-  return !visible;
+  nsContainerFrame* f = frame->GetParent();
+  while (f && f->IsFrameOfType(nsBox::eLineParticipant)) {
+    f = f->GetParent();
+  }
+  nsBlockFrame* blockAncestor = do_QueryFrame(f);
+  if (!blockAncestor) {
+    // The container frame doesn't support line breaking.
+    return false;
+  }
+
+  bool valid = false;
+  nsBlockInFlowLineIterator iter(blockAncestor, frame, &valid);
+  if (!valid) {
+    return false;
+  }
+
+  bool lineNonEmpty = LineHasNonEmptyContent(iter.GetLine());
+
+  while (iter.Next()) {
+    auto currentLine = iter.GetLine();
+    // Completely skip empty lines.
+    if (!currentLine->IsEmpty()) {
+      // If we come across an inline line, the BR has caused a visible line break.
+      if (currentLine->IsInline()) {
+        return false;
+      }
+    }
+  }
+
+  return lineNonEmpty;
 }
 
 nsresult
@@ -1047,6 +1107,9 @@ nsDocumentEncoder::EncodeToStringWithMaxLength(uint32_t aMaxLength,
   static const size_t bufferSize = 2048;
   if (!mCachedBuffer) {
     mCachedBuffer = nsStringBuffer::Alloc(bufferSize).take();
+    if (NS_WARN_IF(!mCachedBuffer)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
   }
   NS_ASSERTION(!mCachedBuffer->IsReadonly(),
                "DocumentEncoder shouldn't keep reference to non-readonly buffer!");
@@ -1374,10 +1437,6 @@ nsHTMLCopyEncoder::SetSelection(nsISelection* aSelection)
     return NS_ERROR_NULL_POINTER;
   range->GetCommonAncestorContainer(getter_AddRefs(commonParent));
 
-  // Thunderbird's msg compose code abuses the HTML copy encoder and gets
-  // confused if mIsTextWidget ends up becoming true, so for now we skip
-  // this logic in Thunderbird.
-#ifndef MOZ_THUNDERBIRD
   for (nsCOMPtr<nsIContent> selContent(do_QueryInterface(commonParent));
        selContent;
        selContent = selContent->GetParent())
@@ -1388,6 +1447,46 @@ nsHTMLCopyEncoder::SetSelection(nsISelection* aSelection)
       mIsTextWidget = true;
       break;
     }
+#ifdef MOZ_THUNDERBIRD
+    else if (selContent->IsHTMLElement(nsGkAtoms::body)) {
+      // Currently, setting mIsTextWidget to 'true' will result in the selection
+      // being encoded/copied as pre-formatted plain text.
+      // This is fine for copying pre-formatted plain text with Firefox, it is
+      // already not correct for copying pre-formatted "rich" text (bold, colour)
+      // with Firefox. As long as the serialisers aren't fixed, copying
+      // pre-formatted text in Firefox is broken. If we set mIsTextWidget,
+      // pre-formatted plain text is copied, but pre-formatted "rich" text loses
+      // the "rich" formatting. If we don't set mIsTextWidget, "rich" text
+      // attributes aren't lost, but white-space is lost.
+      // So far the story for Firefox.
+      //
+      // Thunderbird has two *conflicting* requirements.
+      // Case 1:
+      // When selecting and copying text, even pre-formatted text, as a quote
+      // to be placed into a reply, we *always* expect HTML to be copied.
+      // Case 2:
+      // When copying text in a so-called "plain text" message, that is
+      // one where the body carries style "white-space:pre-wrap", the text should
+      // be copied as pre-formatted plain text.
+      //
+      // Therefore the following code checks for "pre-wrap" on the body.
+      // This is a terrible hack.
+      //
+      // The proper fix would be this:
+      // For case 1:
+      // Communicate the fact that HTML is required to EncodeToString(),
+      // bug 1141786.
+      // For case 2:
+      // Wait for Firefox to get fixed to detect pre-formatting correctly,
+      // bug 1174452.
+      nsAutoString styleVal;
+      if (selContent->GetAttr(kNameSpaceID_None, nsGkAtoms::style, styleVal) &&
+          styleVal.Find(NS_LITERAL_STRING("pre-wrap")) != kNotFound) {
+        mIsTextWidget = true;
+        break;
+      }
+    }
+#endif
   }
 
   // normalize selection if we are not in a widget
@@ -1397,11 +1496,7 @@ nsHTMLCopyEncoder::SetSelection(nsISelection* aSelection)
     mMimeType.AssignLiteral("text/plain");
     return NS_OK;
   }
-#endif
 
-  // XXX For better performance, we should try to get rid of the
-  // Selection object here. See BMO bug 1245883
-  
   // also consider ourselves in a text widget if we can't find an html document
   nsCOMPtr<nsIHTMLDocument> htmlDoc = do_QueryInterface(mDocument);
   if (!(htmlDoc && mDocument->IsHTMLDocument())) {