Fix pixel snapping issues when layers become composited

Source/core/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 98 matching lines @@
 
     // Whether the given layer needs an extra 'contents' layer.
     bool needsContentsCompositingLayer(const RenderLayer*) const;
 
     bool supportsFixedRootBackgroundCompositing() const;
     bool needsFixedRootBackgroundLayer(const RenderLayer*) const;
     GraphicsLayer* fixedRootBackgroundLayer() const;
 
     // Return the bounding box required for compositing layer and its childern, relative to ancestorLayer.
     // If layerBoundingBox is not 0, on return it contains the bounding box of this layer only.
-    IntRect calculateCompositedBounds(const RenderLayer*, const RenderLayer* ancestorLayer) const;
+    LayoutRect calculateCompositedBounds(const RenderLayer*, const RenderLayer* ancestorLayer) const;
 
     // Repaint the appropriate layers when the given RenderLayer starts or stops being composited.
     void repaintOnCompositingChange(RenderLayer*);
 
     void repaintInCompositedAncestor(RenderLayer*, const LayoutRect&);
 
     // Notify us that a layer has been added or removed
     void layerWasAdded(RenderLayer* parent, RenderLayer* child);
     void layerWillBeRemoved(RenderLayer* parent, RenderLayer* child);
 
@@ skipping 230 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