Make squashing work with subpixel layout

Source/core/rendering/compositing/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 199 matching lines @@
         RemoveFromSquashingLayer
     };
 
     struct SquashingState {
         SquashingState()
             : mostRecentMapping(0)
             , hasMostRecentMapping(false)
             , nextSquashedLayerIndex(0)
             , clippingAncestorForMostRecentMapping(0) { }
 
-        void updateSquashingStateForNewMapping(CompositedLayerMappingPtr, bool hasNewCompositedLayerMapping, IntPoint newOffsetFromAbsoluteForSquashingCLM, RenderLayer* clippingAncestorForMostRecentMapping);
+        void updateSquashingStateForNewMapping(CompositedLayerMappingPtr, bool hasNewCompositedLayerMapping, LayoutPoint newOffsetFromAbsoluteForSquashingCLM, RenderLayer* clippingAncestorForMostRecentMapping);
 
         // The most recent composited backing that the layer should squash onto if needed.
         CompositedLayerMappingPtr mostRecentMapping;
         bool hasMostRecentMapping;
 
         // Absolute coordinates of the compositedLayerMapping's owning layer. This is used for computing the correct
         // positions of renderlayers when they paint into the squashing layer.
-        IntPoint offsetFromAbsoluteForSquashingCLM;
+        LayoutPoint offsetFromAbsoluteForSquashingCLM;
 
         // Counter that tracks what index the next RenderLayer would be if it gets squashed to the current squashing layer.
         size_t nextSquashedLayerIndex;
 
         RenderLayer* clippingAncestorForMostRecentMapping;
     };
 
     bool canSquashIntoCurrentSquashingOwner(const RenderLayer* candidate, const SquashingState&, const RenderLayer* clippingAncestor);
 
     CompositingStateTransitionType computeCompositedLayerUpdate(RenderLayer*);
@@ skipping 133 matching lines @@
     OwnPtr<GraphicsLayer> m_layerForScrollCorner;
 #if USE(RUBBER_BANDING)
     OwnPtr<GraphicsLayer> m_layerForOverhangShadow;
 #endif
 };
 
 
 } // namespace WebCore
 
 #endif // RenderLayerCompositor_h