Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/bindings/v8/V8EventListenerList.cpp

 /*
  * Copyright (C) 2009 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 24 matching lines @@
 #include "bindings/v8/V8Binding.h"
 #include "bindings/v8/V8WorkerGlobalScopeEventListener.h"
 
 namespace WebCore {
 
 PassRefPtr<EventListener> V8EventListenerList::getEventListener(v8::Local<v8::Value> value, bool isAttribute, ListenerLookupType lookup)
 {
     v8::Isolate* isolate = v8::Isolate::GetCurrent();
     v8::Handle<v8::Context> context = isolate->GetCurrentContext();
     if (context.IsEmpty())
-        return 0;
+        return nullptr;
     if (lookup == ListenerFindOnly) {
         // Used by EventTarget::removeEventListener, specifically
         // EventTargetV8Internal::removeEventListenerMethod
         ASSERT(!isAttribute);
         return V8EventListenerList::findWrapper(value, isolate);
     }
     if (toDOMWindow(context))
         return V8EventListenerList::findOrCreateWrapper<V8EventListener>(value, isAttribute, isolate);
     return V8EventListenerList::findOrCreateWrapper<V8WorkerGlobalScopeEventListener>(value, isAttribute, isolate);
 }
 
 } // namespace WebCore