Make squashing work with subpixel layout

Source/core/rendering/RenderLayerCompositor.h

Index: Source/core/rendering/RenderLayerCompositor.h
diff --git a/Source/core/rendering/RenderLayerCompositor.h b/Source/core/rendering/RenderLayerCompositor.h
index 933aaf71be47fec013b7d262bc295e210fcdea7e..5fee6600cbd7b5b6307e2bc97b509e8c321408f5 100644
--- a/Source/core/rendering/RenderLayerCompositor.h
+++ b/Source/core/rendering/RenderLayerCompositor.h
@@ -238,7 +238,7 @@ private:
             , hasMostRecentMapping(false)
             , nextSquashedLayerIndex(0) { }
 
-        void updateSquashingStateForNewMapping(CompositedLayerMappingPtr, bool hasNewCompositedLayerMapping, IntPoint newOffsetFromAbsoluteForSquashingCLM);
+        void updateSquashingStateForNewMapping(CompositedLayerMappingPtr, bool hasNewCompositedLayerMapping, LayoutPoint newOffsetFromAbsoluteForSquashingCLM);
 
         // The most recent composited backing that the layer should squash onto if needed.
         CompositedLayerMappingPtr mostRecentMapping;
@@ -246,7 +246,7 @@ private:
 
         // 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;