Set up clip and scroll parents on the blink side.

Source/core/rendering/RenderLayerCompositor.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 86 matching lines @@
 
     // Update the compositing state of the given layer. Returns true if that state changed.
     enum CompositingChangeRepaint { CompositingChangeRepaintNow, CompositingChangeWillRepaintLater };
     bool updateLayerCompositingState(RenderLayer*, CompositingChangeRepaint = CompositingChangeRepaintNow);
 
     // Update the geometry for compositing children of compositingAncestor.
     void updateCompositingDescendantGeometry(RenderLayer* compositingAncestor, RenderLayer*, bool compositedChildrenOnly);
 
     // Whether layer's backing needs a graphics layer to do clipping by an ancestor (non-stacking-context parent with overflow).
     bool clippedByAncestor(RenderLayer*) const;
+    // Whether a layer's backing needs an extra graphics layer to do clipping by a scroll parent.
+    bool clippedByScrollingAncestor(RenderLayer*) const;
     // Whether layer's backing needs a graphics layer to clip z-order children of the given layer.
     bool clipsCompositingDescendants(const RenderLayer*) const;
 
     // Whether the given layer needs an extra 'contents' layer.
     bool needsContentsCompositingLayer(const RenderLayer*) const;
 
     bool supportsFixedRootBackgroundCompositing() const;
     bool needsFixedRootBackgroundLayer(const RenderLayer*) const;
     GraphicsLayer* fixedRootBackgroundLayer() const;
 
@@ skipping 241 matching lines @@
     int m_secondaryCompositedLayerCount; // count of layers that have to be composited because of stacking or overlap.
     double m_obligatoryBackingStoreBytes;
     double m_secondaryBackingStoreBytes;
 #endif
 };
 
 
 } // namespace WebCore
 
 #endif // RenderLayerCompositor_h