Use a boolean hasCompositedLayerMapping() accessor instead of the pointer

Source/web/LinkHighlight.cpp

 /*
  * Copyright (C) 2012 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 113 matching lines @@
     RenderLayer* renderLayer = repaintContainer->layer();
 
     if (!renderLayer || renderLayer->compositingState() == NotComposited)
         return 0;
 
     GraphicsLayer* newGraphicsLayer = renderLayer->compositedLayerMapping()->mainGraphicsLayer();
     m_clipLayer->setSublayerTransform(SkMatrix44());
 
     if (!newGraphicsLayer->drawsContent()) {
         if (renderLayer->scrollableArea()->usesCompositedScrolling()) {
-            ASSERT(renderLayer->compositedLayerMapping() && renderLayer->compositedLayerMapping()->scrollingContentsLayer());
+            ASSERT(renderLayer->hasCompositedLayerMapping() && renderLayer->compositedLayerMapping()->scrollingContentsLayer());
             newGraphicsLayer = renderLayer->compositedLayerMapping()->scrollingContentsLayer();
         } else
             ASSERT_NOT_REACHED();
     }
 
     if (m_currentGraphicsLayer != newGraphicsLayer) {
         if (m_currentGraphicsLayer)
             clearGraphicsLayerLinkHighlightPointer();
 
         m_currentGraphicsLayer = newGraphicsLayer;
@@ skipping 189 matching lines @@
     // Make sure we update geometry on the next callback from WebViewImpl::layout().
     m_geometryNeedsUpdate = true;
 }
 
 WebLayer* LinkHighlight::layer()
 {
     return clipLayer();
 }
 
 } // namespace WeKit