Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/inspector/InspectorDOMDebuggerAgent.cpp

 /*
  * Copyright (C) 2011 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 379 matching lines @@
 }
 
 PassRefPtr<JSONObject> InspectorDOMDebuggerAgent::preparePauseOnNativeEventData(bool isDOMEvent, const String& eventName)
 {
     String fullEventName = (isDOMEvent ? listenerEventCategoryType : instrumentationEventCategoryType) + eventName;
     if (m_pauseInNextEventListener)
         m_pauseInNextEventListener = false;
     else {
         RefPtr<JSONObject> eventListenerBreakpoints = m_state->getObject(DOMDebuggerAgentState::eventListenerBreakpoints);
         if (eventListenerBreakpoints->find(fullEventName) == eventListenerBreakpoints->end())
-            return 0;
+            return nullptr;
     }
 
     RefPtr<JSONObject> eventData = JSONObject::create();
     eventData->setString("eventName", fullEventName);
     return eventData.release();
 }
 
 void InspectorDOMDebuggerAgent::didInstallTimer(ExecutionContext*, int, int, bool)
 {
     pauseOnNativeEventIfNeeded(preparePauseOnNativeEventData(false, setTimerEventName), true);
@@ skipping 106 matching lines @@
 }
 
 void InspectorDOMDebuggerAgent::clear()
 {
     m_domBreakpoints.clear();
     m_pauseInNextEventListener = false;
 }
 
 } // namespace WebCore