Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/timing/Performance.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel 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 34 matching lines @@
 namespace WebCore {
 
 DEFINE_GC_INFO(Performance);
 
 static const size_t defaultResourceTimingBufferSize = 150;
 
 Performance::Performance(Frame* frame)
     : DOMWindowProperty(frame)
     , m_resourceTimingBufferSize(defaultResourceTimingBufferSize)
     , m_referenceTime(frame->document()->loader()->timing()->referenceMonotonicTime())
-    , m_userTiming(0)
+    , m_userTiming(nullptr)
 {
     ASSERT(m_referenceTime);
     ScriptWrappable::init(this);
 }
 
 Performance::~Performance()
 {
 }
 
 const AtomicString& Performance::interfaceName() const
@@ skipping 215 matching lines @@
 
 void Performance::trace(Visitor* visitor)
 {
     visitor->trace(m_navigation);
     visitor->trace(m_timing);
     visitor->trace(m_resourceTimingBuffer);
     visitor->trace(m_userTiming);
 }
 
 } // namespace WebCore