Rework composited scrolling updates.

Source/WebCore/rendering/RenderLayerCompositor.h

Index: Source/WebCore/rendering/RenderLayerCompositor.h
diff --git a/Source/WebCore/rendering/RenderLayerCompositor.h b/Source/WebCore/rendering/RenderLayerCompositor.h
index cc200fb1386640a53a6d3e3ee42033b1c5cabb9a..167a203dcd47c35979375dc8ff8fd9fe96202d30 100644
--- a/Source/WebCore/rendering/RenderLayerCompositor.h
+++ b/Source/WebCore/rendering/RenderLayerCompositor.h
@@ -122,7 +122,9 @@ public:
     
     // Called when something outside WebKit affects the visible rect (e.g. delegated scrolling). Might schedule a layer flush.
     void didChangeVisibleRect();
-    
+
+    void updateLayoutDependentState();
+
     // Rebuild the tree of compositing layers
     void updateCompositingLayers(CompositingUpdateType, RenderLayer* updateRoot = 0);
     
@@ -336,6 +338,9 @@ private:
     bool requiresContentShadowLayer() const;
 #endif
 
+    void updateDescendantsAreContiguousInStackingOrderRecursive(RenderLayer*);
+    void updateNeedsCompositedScrolling(RenderLayer*);
+
 #if !LOG_DISABLED
     const char* logReasonsForCompositing(const RenderLayer*);
     void logLayerInfo(const RenderLayer*, int depth);