Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/webmidi/MIDIConnectionEvent.h

 /*
  * 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 20 matching lines @@
 #ifndef MIDIConnectionEvent_h
 #define MIDIConnectionEvent_h
 
 #include "core/events/Event.h"
 #include "modules/webmidi/MIDIPort.h"
 
 namespace WebCore {
 
 struct MIDIConnectionEventInit : public EventInit {
     MIDIConnectionEventInit()
-        : port(0)
+        : port(nullptr)
     {
     };
 
     RefPtr<MIDIPort> port;
 };
 
 class MIDIConnectionEvent FINAL : public Event {
 public:
     static PassRefPtr<MIDIConnectionEvent> create()
     {
@@ skipping 33 matching lines @@
     {
         ScriptWrappable::init(this);
     }
 
     RefPtr<MIDIPort> m_port;
 };
 
 } // namespace WebCore
 
 #endif // MIDIConnectionEvent_h