Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/page/PointerLockController.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 107 matching lines @@
 void PointerLockController::didNotAcquirePointerLock()
 {
     enqueueEvent(EventTypeNames::webkitpointerlockerror, m_element.get());
     clearElement();
 }
 
 void PointerLockController::didLosePointerLock()
 {
     enqueueEvent(EventTypeNames::webkitpointerlockchange, m_element ? &m_element->document() : m_documentOfRemovedElementWhileWaitingForUnlock.get());
     clearElement();
-    m_documentOfRemovedElementWhileWaitingForUnlock = 0;
+    m_documentOfRemovedElementWhileWaitingForUnlock = nullptr;
 }
 
 void PointerLockController::dispatchLockedMouseEvent(const PlatformMouseEvent& event, const AtomicString& eventType)
 {
     if (!m_element || !m_element->document().frame())
         return;
 
     m_element->dispatchMouseEvent(event, eventType, event.clickCount());
 
     // Create click events
     if (eventType == EventTypeNames::mouseup)
         m_element->dispatchMouseEvent(event, EventTypeNames::click, event.clickCount());
 }
 
 void PointerLockController::clearElement()
 {
     m_lockPending = false;
-    m_element = 0;
+    m_element = nullptr;
 }
 
 void PointerLockController::enqueueEvent(const AtomicString& type, Element* element)
 {
     if (element)
         enqueueEvent(type, &element->document());
 }
 
 void PointerLockController::enqueueEvent(const AtomicString& type, Document* document)
 {
     if (document && document->domWindow())
         document->domWindow()->enqueueDocumentEvent(Event::create(type));
 }
 
 } // namespace WebCore