Add [WillBeGarbageCollected] to Event.idl

Source/core/events/PopStateEvent.h

Index: Source/core/events/PopStateEvent.h
diff --git a/Source/core/events/PopStateEvent.h b/Source/core/events/PopStateEvent.h
index 19f5f88d1285b5088833118e153af465bacc9b82..1d65972114564f3e624eabfea9cbc920729d6c48 100644
--- a/Source/core/events/PopStateEvent.h
+++ b/Source/core/events/PopStateEvent.h
@@ -39,9 +39,9 @@ typedef EventInit PopStateEventInit;
 class PopStateEvent FINAL : public Event {
 public:
     virtual ~PopStateEvent();
-    static PassRefPtr<PopStateEvent> create();
-    static PassRefPtr<PopStateEvent> create(PassRefPtr<SerializedScriptValue>, PassRefPtr<History>);
-    static PassRefPtr<PopStateEvent> create(const AtomicString&, const PopStateEventInit&);
+    static PassRefPtrWillBeRawPtr<PopStateEvent> create();
+    static PassRefPtrWillBeRawPtr<PopStateEvent> create(PassRefPtr<SerializedScriptValue>, PassRefPtr<History>);
+    static PassRefPtrWillBeRawPtr<PopStateEvent> create(const AtomicString&, const PopStateEventInit&);
 
     SerializedScriptValue* serializedState() const { return m_serializedState.get(); }
     void setSerializedState(PassRefPtr<SerializedScriptValue> state)