message: [core] Notifier constructor accepts no args
diff: @@ -167,7 +167,7 @@ function notifierForEvent(object: any, eventName: string, createIfUndefined = fa
  }
  let notifier = object._eventedNotifiers[eventName];
  if (!notifier && createIfUndefined) {
  - notifier = object._eventedNotifiers[eventName] = new Notifier(object);
  + notifier = object._eventedNotifiers[eventName] = new Notifier();
  }
  return notifier;
  }
  