Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/mediastream/RTCDataChannel.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
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 45 matching lines @@
 {
     ASSERT(handler);
     return adoptRef(new RTCDataChannel(context, handler));
 }
 
 PassRefPtr<RTCDataChannel> RTCDataChannel::create(ExecutionContext* context, blink::WebRTCPeerConnectionHandler* peerConnectionHandler, const String& label, const blink::WebRTCDataChannelInit& init, ExceptionState& exceptionState)
 {
     OwnPtr<blink::WebRTCDataChannelHandler> handler = adoptPtr(peerConnectionHandler->createDataChannel(label, init));
     if (!handler) {
         exceptionState.throwDOMException(NotSupportedError, "RTCDataChannel is not supported");
-        return 0;
+        return nullptr;
     }
     return adoptRef(new RTCDataChannel(context, handler.release()));
 }
 
 RTCDataChannel::RTCDataChannel(ExecutionContext* context, PassOwnPtr<blink::WebRTCDataChannelHandler> handler)
     : m_executionContext(context)
     , m_handler(handler)
     , m_stopped(false)
     , m_readyState(ReadyStateConnecting)
     , m_binaryType(BinaryTypeArrayBuffer)
@@ skipping 231 matching lines @@
     events.swap(m_scheduledEvents);
 
     Vector<RefPtr<Event> >::iterator it = events.begin();
     for (; it != events.end(); ++it)
         dispatchEvent((*it).release());
 
     events.clear();
 }
 
 } // namespace WebCore