Set up scroll and clip parents

Source/core/rendering/RenderLayer.h

Index: Source/core/rendering/RenderLayer.h
diff --git a/Source/core/rendering/RenderLayer.h b/Source/core/rendering/RenderLayer.h
index 548b5cf6f1748510fa0c1479696a618d5ebbbc80..a81d6bb356af2e0154e5b1694b515964c7f9fc49 100644
--- a/Source/core/rendering/RenderLayer.h
+++ b/Source/core/rendering/RenderLayer.h
@@ -715,6 +715,10 @@ public:
     void clearBacking(bool layerBeingDestroyed = false);
     bool needsCompositedScrolling() const;
     bool needsToBeStackingContainer() const;
+
+    RenderLayer* scrollParent() const;
+    RenderLayer* clipParent() 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;
@@ -982,6 +986,7 @@ private:
 
 public:
     GraphicsLayer* layerForScrolling() const;
+    GraphicsLayer* layerForScrollChild() const;
     GraphicsLayer* layerForHorizontalScrollbar() const;
     GraphicsLayer* layerForVerticalScrollbar() const;
     GraphicsLayer* layerForScrollCorner() const;