Cache the absolute bounding box rect on RenderLayer.

Source/core/rendering/compositing/GraphicsLayerUpdater.cpp

 /*
  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Google 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
@@ skipping 61 matching lines @@
     CompositedLayerMappingPtr currentCompositedLayerMapping = layer.compositedLayerMapping();
 
     updateType = update(layer, updateType);
 
     // Grab some stats for histograms.
     if (hasCompositedLayerMapping) {
         m_pixelsWithoutPromotingAllTransitions += layer.size().height() * layer.size().width();
     } else {
         if ((layer.renderer()->style()->transitionForProperty(CSSPropertyOpacity) ||
              layer.renderer()->style()->transitionForProperty(CSSPropertyWebkitTransform)) &&
-            m_renderView.viewRect().intersects(layer.absoluteBoundingBox()))
+            m_renderView.viewRect().intersects(layer.cachedAbsoluteBoundingBox()))
             m_pixelsAddedByPromotingAllTransitions += layer.size().height() * layer.size().width();
     }
 
     // If this layer has a compositedLayerMapping, then that is where we place subsequent children GraphicsLayers.
     // Otherwise children continue to append to the child list of the enclosing layer.
     GraphicsLayerVector layerChildren;
     GraphicsLayerVector& childList = hasCompositedLayerMapping ? layerChildren : childLayersOfEnclosingLayer;
 
 #if !ASSERT_DISABLED
     LayerListMutationDetector mutationChecker(layer.stackingNode());
@@ skipping 87 matching lines @@
     if (!layer.parent())
         layer.compositor()->updateRootLayerPosition();
 
     if (mapping->hasUnpositionedOverflowControlsLayers())
         layer.scrollableArea()->positionOverflowControls();
 
     return updateType;
 }
 
 } // namespace WebCore