factory constructor CompositionEvent

Source

factory CompositionEvent(String type,
    {bool canBubble: false, bool cancelable: false, Window view,
    String data, String locale}) {
  if (view == null) {
    view = window;
  }
  CompositionEvent e = document._createEvent("CompositionEvent");

    e._initCompositionEvent(type, canBubble, cancelable, view, data);

  return e;
}