1 files changed, 36 insertions, 26 deletions

diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
index 3ed3b0bb3..dd1b15f77 100644
--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -3031,7 +3031,6 @@ struct HoveredStateComparator
 
 void
 ScrollFrameHelper::AppendScrollPartsTo(nsDisplayListBuilder*   aBuilder,
-                                       const nsRect&           aDirtyRect,
                                        const nsDisplayListSet& aLists,
                                        bool                    aCreateLayer,
                                        bool                    aPositioned)
@@ -3093,23 +3092,25 @@ ScrollFrameHelper::AppendScrollPartsTo(nsDisplayListBuilder*   aBuilder,
     // zoomable, and where the scrollbar sizes are bounded by the widget.
     nsRect dirty = mIsRoot && mOuter->PresContext()->IsRootContentDocument()
                    ? scrollParts[i]->GetVisualOverflowRectRelativeToParent()
-                   : aDirtyRect;
-    nsDisplayListBuilder::AutoBuildingDisplayList
-      buildingForChild(aBuilder, scrollParts[i],
-                       dirty + mOuter->GetOffsetTo(scrollParts[i]), true);
+                   : aBuilder->GetDirtyRect();
 
     // Always create layers for overlay scrollbars so that we don't create a
     // giant layer covering the whole scrollport if both scrollbars are visible.
     bool isOverlayScrollbar = (flags != 0) && overlayScrollbars;
     bool createLayer = aCreateLayer || isOverlayScrollbar;
 
-    nsDisplayListBuilder::AutoCurrentScrollbarInfoSetter
-      infoSetter(aBuilder, scrollTargetId, flags, createLayer);
-    nsDisplayListCollection partList;
-    mOuter->BuildDisplayListForChild(
-      aBuilder, scrollParts[i], dirty, partList,
-      nsIFrame::DISPLAY_CHILD_FORCE_STACKING_CONTEXT);
-
+    nsDisplayListCollection partList(aBuilder);
+    {
+      nsDisplayListBuilder::AutoBuildingDisplayList
+        buildingForChild(aBuilder, mOuter,
+                         dirty, true);
+
+      nsDisplayListBuilder::AutoCurrentScrollbarInfoSetter
+        infoSetter(aBuilder, scrollTargetId, flags, createLayer);
+      mOuter->BuildDisplayListForChild(
+        aBuilder, scrollParts[i], partList,
+        nsIFrame::DISPLAY_CHILD_FORCE_STACKING_CONTEXT);
+    }
     if (createLayer) {
       appendToTopFlags |= APPEND_OWN_LAYER;
     }
@@ -3117,11 +3118,18 @@ ScrollFrameHelper::AppendScrollPartsTo(nsDisplayListBuilder*   aBuilder,
       appendToTopFlags |= APPEND_POSITIONED;
     }
 
+    {
+     nsDisplayListBuilder::AutoBuildingDisplayList
+       buildingForChild(aBuilder, scrollParts[i],
+                        dirty + mOuter->GetOffsetTo(scrollParts[i]), true);
+     nsDisplayListBuilder::AutoCurrentScrollbarInfoSetter
+       infoSetter(aBuilder, scrollTargetId, flags, createLayer);
     // DISPLAY_CHILD_FORCE_STACKING_CONTEXT put everything into
     // partList.PositionedDescendants().
     ::AppendToTop(aBuilder, aLists,
                   partList.PositionedDescendants(), scrollParts[i],
                   appendToTopFlags);
+    }
   }
 }
 
@@ -3246,7 +3254,6 @@ ClipListsExceptCaret(nsDisplayListCollection* aLists,
 
 void
 ScrollFrameHelper::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
-                                    const nsRect&           aDirtyRect,
                                     const nsDisplayListSet& aLists)
 {
   if (aBuilder->IsForFrameVisibility()) {
@@ -3283,7 +3290,7 @@ ScrollFrameHelper::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   // had dirty rects saved for them by their parent frames calling
   // MarkOutOfFlowChildrenForDisplayList, so it's safe to restrict our
   // dirty rect here.
-  nsRect dirtyRect = aDirtyRect;
+  nsRect dirtyRect = aBuilder->GetDirtyRect();
   if (!ignoringThisScrollFrame) {
     dirtyRect = dirtyRect.Intersect(mScrollPort);
   }
@@ -3325,20 +3332,20 @@ ScrollFrameHelper::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 
     if (addScrollBars) {
       // Add classic scrollbars.
-      AppendScrollPartsTo(aBuilder, aDirtyRect, aLists,
-                          createLayersForScrollbars, false);
+      AppendScrollPartsTo(aBuilder, aLists, createLayersForScrollbars, false);
     }
 
+  nsDisplayListBuilder::AutoBuildingDisplayList
+    building(aBuilder, mOuter, dirtyRect, aBuilder->IsAtRootOfPseudoStackingContext());
+
     // Don't clip the scrolled child, and don't paint scrollbars/scrollcorner.
     // The scrolled frame shouldn't have its own background/border, so we
     // can just pass aLists directly.
-    mOuter->BuildDisplayListForChild(aBuilder, mScrolledFrame,
-                                     dirtyRect, aLists);
+    mOuter->BuildDisplayListForChild(aBuilder, mScrolledFrame, aLists);
 
     if (addScrollBars) {
       // Add overlay scrollbars.
-      AppendScrollPartsTo(aBuilder, aDirtyRect, aLists,
-                          createLayersForScrollbars, true);
+      AppendScrollPartsTo(aBuilder, aLists, createLayersForScrollbars, true);
     }
 
     return;
@@ -3376,8 +3383,7 @@ ScrollFrameHelper::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   // Note that this does not apply for overlay scrollbars; those are drawn
   // in the positioned-elements layer on top of everything else by the call
   // to AppendScrollPartsTo(..., true) further down.
-  AppendScrollPartsTo(aBuilder, aDirtyRect, aLists,
-                      createLayersForScrollbars, false);
+  AppendScrollPartsTo(aBuilder, aLists, createLayersForScrollbars, false);
 
   const nsStyleDisplay* disp = mOuter->StyleDisplay();
   if (disp && (disp->mWillChangeBitField & NS_STYLE_WILL_CHANGE_SCROLL)) {
@@ -3414,7 +3420,7 @@ ScrollFrameHelper::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   nsIScrollableFrame* sf = do_QueryFrame(mOuter);
   MOZ_ASSERT(sf);
 
-  nsDisplayListCollection scrolledContent;
+  nsDisplayListCollection scrolledContent(aBuilder);
   {
     // Note that setting the current scroll parent id here means that positioned children
     // of this scroll info layer will pick up the scroll info layer as their scroll handoff
@@ -3506,7 +3512,10 @@ ScrollFrameHelper::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
       scrolledRectClipState.ClipContainingBlockDescendants(
         scrolledRectClip + aBuilder->ToReferenceFrame(mOuter));
 
-      mOuter->BuildDisplayListForChild(aBuilder, mScrolledFrame, dirtyRect, scrolledContent);
+      nsDisplayListBuilder::AutoBuildingDisplayList
+      building(aBuilder, mOuter, dirtyRect, aBuilder->IsAtRootOfPseudoStackingContext());
+
+      mOuter->BuildDisplayListForChild(aBuilder, mScrolledFrame, scrolledContent);
     }
 
     if (contentBoxClipForNonCaretContent) {
@@ -3593,8 +3602,8 @@ ScrollFrameHelper::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
     }
   }
   // Now display overlay scrollbars and the resizer, if we have one.
-  AppendScrollPartsTo(aBuilder, aDirtyRect, scrolledContent,
-                      createLayersForScrollbars, true);
+  AppendScrollPartsTo(aBuilder, scrolledContent, createLayersForScrollbars, true);
+
   scrolledContent.MoveTo(aLists);
 }
 
@@ -6175,3 +6184,4 @@ ScrollFrameHelper::UsesContainerScrolling() const
   }
   return false;
 }
+