Store the overflow out of flows as an nsFrameList. b=516974 r=bzbarsky

layout/generic/nsBlockFrame.cpp

@@ -534,7 +534,8 @@ nsBlockFrame::GetChildList(nsIAtom* aListName) const
                          : nsFrameList::EmptyList();
   }
   else if (aListName == nsGkAtoms::overflowOutOfFlowList) {
-    return GetOverflowOutOfFlows();
+    const nsFrameList* list = GetOverflowOutOfFlows();
+    return list ? *list : nsFrameList::EmptyList();
   }
   else if (aListName == nsGkAtoms::floatList) {
     return mFloats;
@@ -4522,35 +4523,46 @@ nsBlockFrame::SetOverflowLines(nsLineList* aOverflowLines)
   return rv;
 }
 
-nsFrameList
+nsFrameList*
 nsBlockFrame::GetOverflowOutOfFlows() const
 {
   if (!(GetStateBits() & NS_BLOCK_HAS_OVERFLOW_OUT_OF_FLOWS)) {
-    return nsFrameList();
+    return nsnull;
   }
-  nsIFrame* result = static_cast<nsIFrame*>
-                                (GetProperty(nsGkAtoms::overflowOutOfFlowsProperty));
+  nsFrameList* result =
+    GetPropTableFrames(PresContext(), nsGkAtoms::overflowOutOfFlowsProperty);
   NS_ASSERTION(result, "value should always be non-empty when state set");
-  return nsFrameList(result, nsLayoutUtils::GetLastSibling(result));
+  return result;
 }
 
 // This takes ownership of the frames
 void
-nsBlockFrame::SetOverflowOutOfFlows(const nsFrameList& aList)
+nsBlockFrame::SetOverflowOutOfFlows(const nsFrameList& aList,
+                                    nsFrameList* aPropValue)
 {
+  NS_PRECONDITION(!!(GetStateBits() & NS_BLOCK_HAS_OVERFLOW_OUT_OF_FLOWS) ==
+                  !!aPropValue, "state does not match value");
+
   if (aList.IsEmpty()) {
     if (!(GetStateBits() & NS_BLOCK_HAS_OVERFLOW_OUT_OF_FLOWS)) {
       return;
     }
-#ifdef DEBUG
-    nsIFrame* result = static_cast<nsIFrame*>
-#endif
-      (UnsetProperty(nsGkAtoms::overflowOutOfFlowsProperty));
-    NS_ASSERTION(result, "value should always be non-empty when state set");
+    nsFrameList* list =
+      RemovePropTableFrames(PresContext(),
+                            nsGkAtoms::overflowOutOfFlowsProperty);
+    NS_ASSERTION(aPropValue == list, "prop value mismatch");
+    delete list;
     RemoveStateBits(NS_BLOCK_HAS_OVERFLOW_OUT_OF_FLOWS);
-  } else {
-    SetProperty(nsGkAtoms::overflowOutOfFlowsProperty,
-                aList.FirstChild(), nsnull);
+  }
+  else if (GetStateBits() & NS_BLOCK_HAS_OVERFLOW_OUT_OF_FLOWS) {
+    NS_ASSERTION(aPropValue == GetPropTableFrames(PresContext(),
+                                 nsGkAtoms::overflowOutOfFlowsProperty),
+                 "prop value mismatch");
+    *aPropValue = aList;
+  }
+  else {
+    SetPropTableFrames(PresContext(), new nsFrameList(aList),
+                       nsGkAtoms::overflowOutOfFlowsProperty);
     AddStateBits(NS_BLOCK_HAS_OVERFLOW_OUT_OF_FLOWS);
   }
 }
@@ -6674,8 +6686,8 @@ nsBlockFrame::CheckFloats(nsBlockReflowState& aState)
   }
 #endif
 
-  nsFrameList oofs = GetOverflowOutOfFlows();
-  if (oofs.NotEmpty()) {
+  const nsFrameList* oofs = GetOverflowOutOfFlows();
+  if (oofs && oofs->NotEmpty()) {
     // Floats that were pushed should be removed from our float
     // manager.  Otherwise the float manager's YMost or XMost might
     // be larger than necessary, causing this block to get an
@@ -6686,7 +6698,7 @@ nsBlockFrame::CheckFloats(nsBlockReflowState& aState)
     // because we know from here on the float manager will only be
     // used for its XMost and YMost, not to place new floats and
     // lines.
-    aState.mFloatManager->RemoveTrailingRegions(oofs.FirstChild());
+    aState.mFloatManager->RemoveTrailingRegions(oofs->FirstChild());
   }
 }
 

layout/generic/nsBlockFrame.h

@@ -677,30 +677,28 @@ protected:
    * overflow list. It gives the client direct writable access to
    * the frame list temporarily but ensures that property is only
    * written back if absolutely necessary.
-   * @note currently we can ignore mList.mLastChild being different because
-   * the overflow OOFs are stored internally as a frame pointer property
-   * (the first child of the list).
    */
   struct nsAutoOOFFrameList {
     nsFrameList mList;
 
     nsAutoOOFFrameList(nsBlockFrame* aBlock)
-      : mList(aBlock->GetOverflowOutOfFlows())
-      , mOldFirstChild(mList.FirstChild())
-      , mBlock(aBlock) {}
-    ~nsAutoOOFFrameList() {
-      if (mList.FirstChild() != mOldFirstChild) {
-        mBlock->SetOverflowOutOfFlows(mList);
+      : mPropValue(aBlock->GetOverflowOutOfFlows())
+      , mBlock(aBlock) {
+      if (mPropValue) {
+        mList = *mPropValue;
       }
     }
+    ~nsAutoOOFFrameList() {
+      mBlock->SetOverflowOutOfFlows(mList, mPropValue);
+    }
   protected:
-    nsIFrame* const mOldFirstChild;
+    nsFrameList* const mPropValue;
     nsBlockFrame* const mBlock;
   };
   friend struct nsAutoOOFFrameList;
 
-  nsFrameList GetOverflowOutOfFlows() const;
-  void SetOverflowOutOfFlows(const nsFrameList& aList);
+  nsFrameList* GetOverflowOutOfFlows() const;
+  void SetOverflowOutOfFlows(const nsFrameList& aList, nsFrameList* aPropValue);
 
 #ifdef NS_DEBUG
   void VerifyLines(PRBool aFinalCheckOK);