Set up clip and scroll parents on the blink side.

Source/core/rendering/RenderLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 586 matching lines @@
     // paints the layers that intersect the damage rect from back to
     // front.  The hitTest method looks for mouse events by walking
     // layers that intersect the point from front to back.
     void paint(GraphicsContext*, const LayoutRect& damageRect, PaintBehavior = PaintBehaviorNormal, RenderObject* paintingRoot = 0,
         RenderRegion* = 0, PaintLayerFlags = 0);
     bool hitTest(const HitTestRequest&, HitTestResult&);
     bool hitTest(const HitTestRequest&, const HitTestLocation&, HitTestResult&);
     void paintOverlayScrollbars(GraphicsContext*, const LayoutRect& damageRect, PaintBehavior, RenderObject* paintingRoot = 0);
 
     struct ClipRectsContext {
-        ClipRectsContext(const RenderLayer* inRootLayer, RenderRegion* inRegion, ClipRectsType inClipRectsType, OverlayScrollbarSizeRelevancy inOverlayScrollbarSizeRelevancy = IgnoreOverlayScrollbarSize, ShouldRespectOverflowClip inRespectOverflowClip = RespectOverflowClip)
+        ClipRectsContext(const RenderLayer* inRootLayer, RenderRegion* inRegion, ClipRectsType inClipRectsType, OverlayScrollbarSizeRelevancy inOverlayScrollbarSizeRelevancy = IgnoreOverlayScrollbarSize, ShouldRespectOverflowClip inRespectOverflowClip = RespectOverflowClip, const RenderLayer* scrollParent = 0)
             : rootLayer(inRootLayer)
             , region(inRegion)
             , clipRectsType(inClipRectsType)
             , overlayScrollbarSizeRelevancy(inOverlayScrollbarSizeRelevancy)
             , respectOverflowClip(inRespectOverflowClip)
         { }
         const RenderLayer* rootLayer;
         RenderRegion* region;
         ClipRectsType clipRectsType;
         OverlayScrollbarSizeRelevancy overlayScrollbarSizeRelevancy;
@@ skipping 97 matching lines @@
     void operator delete(void*);
 
     bool isComposited() const { return m_backing != 0; }
     bool hasCompositedMask() const;
     RenderLayerBacking* backing() const { return m_backing.get(); }
     RenderLayerBacking* ensureBacking();
     void clearBacking(bool layerBeingDestroyed = false);
     bool adjustForForceCompositedScrollingMode(bool) const;
     bool needsCompositedScrolling() const;
     bool needsToBeStackingContainer() const;
+
+    bool hasScrollParent() const;
+
     bool needsCompositingLayersRebuiltForClip(const RenderStyle* oldStyle, const RenderStyle* newStyle) const;
     bool needsCompositingLayersRebuiltForOverflow(const RenderStyle* oldStyle, const RenderStyle* newStyle) const;
     bool needsCompositingLayersRebuiltForFilters(const RenderStyle* oldStyle, const RenderStyle* newStyle, bool didPaintWithFilters) const;
 
     bool paintsWithTransparency(PaintBehavior paintBehavior) const
     {
         return isTransparent() && ((paintBehavior & PaintBehaviorFlattenCompositingLayers) || !isComposited());
     }
 
     bool paintsWithTransform(PaintBehavior) const;
@@ skipping 260 matching lines @@
     bool shouldBeSelfPaintingLayer() const;
 
     // Start of ScrollableArea interface
     // To be moved to RenderLayerScrollableArea
     ScrollableArea* enclosingScrollableArea() const;
 
     void updateNeedsCompositedScrolling();
 
 public:
     GraphicsLayer* layerForScrolling() const;
+    GraphicsLayer* layerForScrollChild() const;
     GraphicsLayer* layerForHorizontalScrollbar() const;
     GraphicsLayer* layerForVerticalScrollbar() const;
     GraphicsLayer* layerForScrollCorner() const;
     Scrollbar* horizontalScrollbar() const { return m_hBar.get(); }
     Scrollbar* verticalScrollbar() const { return m_vBar.get(); }
     bool usesCompositedScrolling() const;
 
     bool hasOverlayScrollbars() const;
 
     int scrollXOffset() const;
@@ skipping 312 matching lines @@
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const WebCore::RenderLayer*);
 void showLayerTree(const WebCore::RenderObject*);
 #endif
 
 #endif // RenderLayer_h