Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/events/MessageEvent.h

Index: Source/core/events/MessageEvent.h
diff --git a/Source/core/events/MessageEvent.h b/Source/core/events/MessageEvent.h
index 1442bf4132376e92657957080689e87bc6a67e5c..0adabec93bc65ea024e3abce4379b77b45dfd38c 100644
--- a/Source/core/events/MessageEvent.h
+++ b/Source/core/events/MessageEvent.h
@@ -53,15 +53,15 @@ public:
     {
         return adoptRef(new MessageEvent);
     }
-    static PassRefPtr<MessageEvent> create(PassOwnPtr<MessagePortArray> ports, const String& origin = String(), const String& lastEventId = String(), PassRefPtr<EventTarget> source = 0)
+    static PassRefPtr<MessageEvent> create(PassOwnPtr<MessagePortArray> ports, const String& origin = String(), const String& lastEventId = String(), PassRefPtr<EventTarget> source = nullptr)
     {
         return adoptRef(new MessageEvent(origin, lastEventId, source, ports));
     }
-    static PassRefPtr<MessageEvent> create(PassOwnPtr<MessagePortArray> ports, PassRefPtr<SerializedScriptValue> data, const String& origin = String(), const String& lastEventId = String(), PassRefPtr<EventTarget> source = 0)
+    static PassRefPtr<MessageEvent> create(PassOwnPtr<MessagePortArray> ports, PassRefPtr<SerializedScriptValue> data, const String& origin = String(), const String& lastEventId = String(), PassRefPtr<EventTarget> source = nullptr)
     {
         return adoptRef(new MessageEvent(data, origin, lastEventId, source, ports));
     }
-    static PassRefPtr<MessageEvent> create(PassOwnPtr<MessagePortChannelArray> channels, PassRefPtr<SerializedScriptValue> data, const String& origin = String(), const String& lastEventId = String(), PassRefPtr<EventTarget> source = 0)
+    static PassRefPtr<MessageEvent> create(PassOwnPtr<MessagePortChannelArray> channels, PassRefPtr<SerializedScriptValue> data, const String& origin = String(), const String& lastEventId = String(), PassRefPtr<EventTarget> source = nullptr)
     {
         return adoptRef(new MessageEvent(data, origin, lastEventId, source, channels));
     }