Add [WillBeGarbageCollected] to Event.idl

Source/core/events/CustomEvent.h

Index: Source/core/events/CustomEvent.h
diff --git a/Source/core/events/CustomEvent.h b/Source/core/events/CustomEvent.h
index a2ae1953374c9764a629955a0ba30a1c7fe97824..e4165837848a424e80e76e0114f8a2c7bdcbbd83 100644
--- a/Source/core/events/CustomEvent.h
+++ b/Source/core/events/CustomEvent.h
@@ -38,14 +38,14 @@ class CustomEvent FINAL : public Event {
 public:
     virtual ~CustomEvent();
 
-    static PassRefPtr<CustomEvent> create()
+    static PassRefPtrWillBeRawPtr<CustomEvent> create()
     {
-        return adoptRef(new CustomEvent);
+        return adoptRefCountedWillBeRefCountedGarbageCollected(new CustomEvent);
     }
 
-    static PassRefPtr<CustomEvent> create(const AtomicString& type, const CustomEventInit& initializer)
+    static PassRefPtrWillBeRawPtr<CustomEvent> create(const AtomicString& type, const CustomEventInit& initializer)
     {
-        return adoptRef(new CustomEvent(type, initializer));
+        return adoptRefCountedWillBeRefCountedGarbageCollected(new CustomEvent(type, initializer));
     }
 
     void initCustomEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtr<SerializedScriptValue>);