Bug 983465. Disable collapsing-text frame construction optimization on a per-document basis. r=bz

--HG--
extra : rebase_source : fc2059ac826e001660fb7233d775f8a046467f6b

content/base/src/nsGenericDOMDataNode.h

@@ -51,10 +51,6 @@ enum {
   // bit is set, and if so it indicates whether we're only whitespace or
   // not.
   NS_TEXT_IS_ONLY_WHITESPACE =            DATA_NODE_FLAG_BIT(3),
-
-  // This bit is set to indicate that we must create frames for this text node
-  // even if it's only whitespace next to a block boundary.
-  NS_CREATE_FRAME_FOR_IGNORABLE_WHITESPACE = DATA_NODE_FLAG_BIT(4)
 };
 
 // Make sure we have enough space for those bits

content/base/src/nsRange.cpp

@@ -2751,8 +2751,10 @@ GetTextFrameForContent(nsIContent* aContent)
 {
   nsIPresShell* presShell = aContent->OwnerDoc()->GetShell();
   if (presShell) {
-    nsIFrame* frame = presShell->FrameConstructor()->EnsureFrameForTextNode(
+    presShell->FrameConstructor()->EnsureFrameForTextNode(
         static_cast<nsGenericDOMDataNode*>(aContent));
+    aContent->OwnerDoc()->FlushPendingNotifications(Flush_Layout);
+    nsIFrame* frame = aContent->GetPrimaryFrame();
     if (frame && frame->GetType() == nsGkAtoms::textFrame) {
       return static_cast<nsTextFrame*>(frame);
     }
@@ -2804,7 +2806,7 @@ static void CollectClientRects(nsLayoutUtils::RectCallback* aCollector,
     return;
   }
 
-  aStartParent->GetCurrentDoc()->FlushPendingNotifications(Flush_Layout);
+  aStartParent->OwnerDoc()->FlushPendingNotifications(Flush_Layout);
 
   // Recheck whether we're still in the document
   if (!aStartParent->IsInDoc()) {

layout/base/nsCSSFrameConstructor.cpp

@@ -1425,6 +1425,7 @@ nsCSSFrameConstructor::nsCSSFrameConstructor(nsIDocument *aDocument,
   , mCountersDirty(false)
   , mIsDestroyingFrameTree(false)
   , mHasRootAbsPosContainingBlock(false)
+  , mAlwaysCreateFramesForIgnorableWhitespace(false)
 {
 #ifdef DEBUG
   static bool gFirstTime = true;
@@ -5552,16 +5553,13 @@ nsCSSFrameConstructor::ConstructFramesFromItem(nsFrameConstructorState& aState,
     // due to dynamic changes.
     // We don't do it for SVG text, since we might need to position and
     // measure the white space glyphs due to x/y/dx/dy attributes.
-    // We check that NS_CREATE_FRAME_FOR_IGNORABLE_WHITESPACE is not set on
-    // the node. This lets us disable this optimization for specific nodes
-    // (e.g. nodes whose geometry is being queried via DOM APIs).
     if (AtLineBoundary(aIter) &&
         !styleContext->StyleText()->WhiteSpaceOrNewlineIsSignificant() &&
         aIter.List()->ParentHasNoXBLChildren() &&
         !(aState.mAdditionalStateBits & NS_FRAME_GENERATED_CONTENT) &&
         (item.mFCData->mBits & FCDATA_IS_LINE_PARTICIPANT) &&
         !(item.mFCData->mBits & FCDATA_IS_SVG_TEXT) &&
-        !item.mContent->HasFlag(NS_CREATE_FRAME_FOR_IGNORABLE_WHITESPACE) &&
+        !mAlwaysCreateFramesForIgnorableWhitespace &&
         item.IsWhitespace(aState))
       return;
 
@@ -7784,13 +7782,15 @@ nsIFrame*
 nsCSSFrameConstructor::EnsureFrameForTextNode(nsGenericDOMDataNode* aContent)
 {
   if (aContent->HasFlag(NS_CREATE_FRAME_IF_NON_WHITESPACE) &&
-      !aContent->HasFlag(NS_CREATE_FRAME_FOR_IGNORABLE_WHITESPACE)) {
+      !mAlwaysCreateFramesForIgnorableWhitespace) {
     // Text frame may have been suppressed. Disable suppression and signal
-    // that a flush should be performed.
+    // that a flush should be performed. We do this on a document-wide
-    aContent->SetFlags(NS_CREATE_FRAME_FOR_IGNORABLE_WHITESPACE);
+    // basis so that pages that repeatedly query metrics for
+    // collapsed-whitespace text nodes don't trigger pathological behavior.
+    mAlwaysCreateFramesForIgnorableWhitespace = true;
     nsAutoScriptBlocker blocker;
     BeginUpdate();
-    RecreateFramesForContent(aContent, false);
+    ReconstructDocElementHierarchy();
     EndUpdate();
   }
   return aContent->GetPrimaryFrame();

layout/base/nsCSSFrameConstructor.h

@@ -1801,6 +1801,7 @@ private:
   bool                mIsDestroyingFrameTree : 1;
   // This is true if mDocElementContainingBlock supports absolute positioning
   bool                mHasRootAbsPosContainingBlock : 1;
+  bool                mAlwaysCreateFramesForIgnorableWhitespace : 1;
 
   nsCOMPtr<nsILayoutHistoryState> mTempFrameTreeState;
 };