Rework composited scrolling updates.

Source/WebCore/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 104 matching lines @@
     void setCompositingLayersNeedRebuild(bool needRebuild = true);
     bool compositingLayersNeedRebuild() const { return m_compositingLayersNeedRebuild; }
 
     // Controls whether or not to consult geometry when deciding which layers need
     // to be composited. Defaults to true.
     void setCompositingConsultsOverlap(bool b) { m_compositingConsultsOverlap = b; }
     bool compositingConsultsOverlap() const { return m_compositingConsultsOverlap; }
     
     // Called when something outside WebKit affects the visible rect (e.g. delegated scrolling). Might schedule a layer flush.
     void didChangeVisibleRect();
-    
+
+    void updateDescendantsAreContiguousInStackingOrderRecursive(RenderLayer*);
+    void updateNeedsCompositedScrolling(RenderLayer*);
+
     // Rebuild the tree of compositing layers
     void updateCompositingLayers(CompositingUpdateType, RenderLayer* updateRoot = 0);
     // This is only used when state changes and we do not exepect a style update or layout to happen soon (e.g. when
     // we discover that an iframe is overlapped during painting).
     void scheduleCompositingLayerUpdate();
     
     // Update the compositing state of the given layer. Returns true if that state changed.
     enum CompositingChangeRepaint { CompositingChangeRepaintNow, CompositingChangeWillRepaintLater };
     bool updateLayerCompositingState(RenderLayer*, CompositingChangeRepaint = CompositingChangeRepaintNow);
 
@@ skipping 265 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