Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/mhtml/ArchiveResource.cpp

 /*
  * Copyright (C) 2008, 2010 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
@@ skipping 27 matching lines @@
     , m_mimeType(mimeType)
     , m_textEncoding(textEncoding)
     , m_frameName(frameName)
 {
     ASSERT(m_data);
 }
 
 PassRefPtr<ArchiveResource> ArchiveResource::create(PassRefPtr<SharedBuffer> data, const KURL& url, const AtomicString& mimeType, const AtomicString& textEncoding, const String& frameName, const ResourceResponse& response)
 {
     if (!data)
-        return 0;
+        return nullptr;
     if (response.isNull()) {
         unsigned dataSize = data->size();
         return adoptRef(new ArchiveResource(data, url, mimeType, textEncoding, frameName,
             ResourceResponse(url, mimeType, dataSize, textEncoding, String())));
     }
     return adoptRef(new ArchiveResource(data, url, mimeType, textEncoding, frameName, response));
 }
 
 PassRefPtr<ArchiveResource> ArchiveResource::create(PassRefPtr<SharedBuffer> data, const KURL& url, const ResourceResponse& response)
 {
     return create(data, url, response.mimeType(), response.textEncodingName(), String(), response);
 }
 
 }