Disable solid background color optimization for composited layers.

Source/core/platform/graphics/GraphicsLayer.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 385 matching lines @@
     String layerTreeAsText(LayerTreeAsTextBehavior = LayerTreeAsTextBehaviorNormal) const;
 
     // Return an estimate of the backing store memory cost (in bytes). May be incorrect for tiled layers.
     virtual double backingStoreMemoryEstimate() const;
 
     void resetTrackedRepaints();
     void addRepaintRect(const FloatRect&);
 
     static bool supportsBackgroundColorContent()
     {
-        return true;
+        return false;
     }
 
     void updateDebugIndicators();
 
     virtual void reportMemoryUsage(MemoryObjectInfo*) const;
 
 protected:
     // Should be called from derived class destructors. Should call willBeDestroyed() on super.
     virtual void willBeDestroyed();
 
@@ skipping 79 matching lines @@
 
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showGraphicsLayerTree(const WebCore::GraphicsLayer* layer);
 #endif
 
 #endif // GraphicsLayer_h