Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/fetch/FontResource.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile, Inc.
  *
  * 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 98 matching lines @@
         if (m_data) {
             m_externalSVGDocument = SVGDocument::create();
 
             OwnPtr<TextResourceDecoder> decoder = TextResourceDecoder::create("application/xml");
             String svgSource = decoder->decode(m_data->data(), m_data->size());
             svgSource = svgSource + decoder->flush();
 
             m_externalSVGDocument->setContent(svgSource);
 
             if (decoder->sawError())
-                m_externalSVGDocument = 0;
+                m_externalSVGDocument = nullptr;
         }
         if (!m_externalSVGDocument)
             setStatus(DecodeError);
     }
 
     return m_externalSVGDocument;
 }
 
 SVGFontElement* FontResource::getSVGFontById(const String& fontName) const
 {
@@ skipping 32 matching lines @@
 }
 
 void FontResource::checkNotify()
 {
     ResourceClientWalker<FontResourceClient> w(m_clients);
     while (FontResourceClient* c = w.next())
         c->fontLoaded(this);
 }
 
 }