Set up scroll and clip parents

Source/core/rendering/RenderLayerCompositor.h

Index: Source/core/rendering/RenderLayerCompositor.h
diff --git a/Source/core/rendering/RenderLayerCompositor.h b/Source/core/rendering/RenderLayerCompositor.h
index 60c77ea12e844f0e97de0a52686966a7dfbd111b..40422e20b5c5451aa6df5a5e9663f151003c32b8 100644
--- a/Source/core/rendering/RenderLayerCompositor.h
+++ b/Source/core/rendering/RenderLayerCompositor.h
@@ -242,10 +242,16 @@ private:
     void computeCompositingRequirements(RenderLayer* ancestorLayer, RenderLayer*, OverlapMap*, struct CompositingState&, bool& layersChanged, bool& descendantHas3DTransform, Vector<RenderLayer*>& unclippedDescendants);
 
     // Recurses down the tree, parenting descendant compositing layers and collecting an array of child layers for the current compositing layer.
-    void rebuildCompositingLayerTree(RenderLayer*, Vector<GraphicsLayer*>& childGraphicsLayersOfEnclosingLayer, int depth);
+    void rebuildCompositingLayerTree(RenderLayer*, Vector<GraphicsLayer*>& childGraphicsLayersOfEnclosingLayer, HashSet<RenderLayer*>& visited, int depth);
+
+    // Ensures that scroll parents have been processed before recurring into rebuildCompositingLayerTree for the current layer.
+    void rebuildCompositingLayerTreeForLayerAndScrollParents(RenderLayer*, Vector<GraphicsLayer*>& childGraphicsLayersOfEnclosingLayer, HashSet<RenderLayer*>& visited, HashMap<RenderLayer*, Vector<GraphicsLayer*> >& childGraphicsLayersOfScrollParents, int depth);
 
     // Recurses down the tree, updating layer geometry only.
-    void updateLayerTreeGeometry(RenderLayer*, int depth);
+    void updateLayerTreeGeometry(RenderLayer*, HashSet<RenderLayer*>& visited, int depth);
+
+    // Ensures that scroll parents have been processed before recurring into updateLayerTree for the current layer.
+    void updateLayerTreeGeometryForLayerAndScrollParents(RenderLayer*, HashSet<RenderLayer*>& visited, int depth);
 
     // Hook compositing layers together
     void setCompositingParent(RenderLayer* childLayer, RenderLayer* parentLayer);