Add [WillBeGarbageCollected] to Event.idl

Source/modules/encryptedmedia/MediaKeyMessageEvent.h

Index: Source/modules/encryptedmedia/MediaKeyMessageEvent.h
diff --git a/Source/modules/encryptedmedia/MediaKeyMessageEvent.h b/Source/modules/encryptedmedia/MediaKeyMessageEvent.h
index bff2d4b1bb5a289346cd29bb3863416f5a4cb1fc..a1f279f3429294288dc9a521ec77742bd52f2dd4 100644
--- a/Source/modules/encryptedmedia/MediaKeyMessageEvent.h
+++ b/Source/modules/encryptedmedia/MediaKeyMessageEvent.h
@@ -43,14 +43,14 @@ class MediaKeyMessageEvent FINAL : public Event {
 public:
     virtual ~MediaKeyMessageEvent();
 
-    static PassRefPtr<MediaKeyMessageEvent> create()
+    static PassRefPtrWillBeRawPtr<MediaKeyMessageEvent> create()
     {
-        return adoptRef(new MediaKeyMessageEvent);
+        return adoptRefWillBeRefCountedGarbageCollected(new MediaKeyMessageEvent);
     }
 
-    static PassRefPtr<MediaKeyMessageEvent> create(const AtomicString& type, const MediaKeyMessageEventInit& initializer)
+    static PassRefPtrWillBeRawPtr<MediaKeyMessageEvent> create(const AtomicString& type, const MediaKeyMessageEventInit& initializer)
     {
-        return adoptRef(new MediaKeyMessageEvent(type, initializer));
+        return adoptRefWillBeRefCountedGarbageCollected(new MediaKeyMessageEvent(type, initializer));
     }
 
     virtual const AtomicString& interfaceName() const OVERRIDE;