Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/inspector/InspectorLayerTreeAgent.cpp

 /*
  * Copyright (C) 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 167 matching lines @@
         .setY(rect.y())
         .setWidth(rect.width())
         .setHeight(rect.height());
     m_frontend->layerPainted(idForLayer(graphicsLayer), domRect.release());
 }
 
 PassRefPtr<TypeBuilder::Array<TypeBuilder::LayerTree::Layer> > InspectorLayerTreeAgent::buildLayerTree()
 {
     RenderLayerCompositor* compositor = renderLayerCompositor();
     if (!compositor || !compositor->inCompositingMode())
-        return 0;
+        return nullptr;
     LayerIdToNodeIdMap layerIdToNodeIdMap;
     RefPtr<TypeBuilder::Array<TypeBuilder::LayerTree::Layer> > layers = TypeBuilder::Array<TypeBuilder::LayerTree::Layer>::create();
     buildLayerIdToNodeIdMap(compositor->rootRenderLayer(), layerIdToNodeIdMap);
     gatherGraphicsLayers(compositor->rootGraphicsLayer(), layerIdToNodeIdMap, layers);
     return layers.release();
 }
 
 void InspectorLayerTreeAgent::buildLayerIdToNodeIdMap(RenderLayer* root, LayerIdToNodeIdMap& layerIdToNodeIdMap)
 {
     if (root->hasCompositedLayerMapping()) {
@@ skipping 179 matching lines @@
     for (size_t i = 0; i < timings->size(); ++i) {
         const Vector<double>& row = (*timings)[i];
         RefPtr<TypeBuilder::Array<double> > outRow = TypeBuilder::Array<double>::create();
         for (size_t j = 1; j < row.size(); ++j)
             outRow->addItem(row[j] - row[j - 1]);
         outTimings->addItem(outRow.release());
     }
 }
 
 } // namespace WebCore