Use a boolean hasCompositedLayerMapping() accessor instead of the pointer

Source/core/rendering/RenderTreeAsText.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 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 533 matching lines @@
         if (l.renderBox() && l.renderBox()->pixelSnappedClientHeight() != l.renderBox()->scrollHeight())
             ts << " scrollHeight " << l.renderBox()->scrollHeight();
     }
 
     if (paintPhase == LayerPaintPhaseBackground)
         ts << " layerType: background only";
     else if (paintPhase == LayerPaintPhaseForeground)
         ts << " layerType: foreground only";
 
     if (behavior & RenderAsTextShowCompositedLayers) {
-        if (l.compositedLayerMapping()) {
+        if (l.hasCompositedLayerMapping()) {
             ts << " (composited, bounds="
                 << l.compositedLayerMapping()->compositedBounds()
                 << ", drawsContent="
                 << l.compositedLayerMapping()->mainGraphicsLayer()->drawsContent()
                 << ", paints into ancestor="
                 << l.compositedLayerMapping()->paintsIntoCompositedAncestor()
                 << ")";
         }
     }
 
@@ skipping 263 matching lines @@
     element->document().updateLayout();
 
     RenderObject* renderer = element->renderer();
     if (!renderer || !renderer->isListItem())
         return String();
 
     return toRenderListItem(renderer)->markerText();
 }
 
 } // namespace WebCore