TransitionEvent(String type, [ Map eventInitDict ])

Source 

@DomName('TransitionEvent.TransitionEvent')
@DocsEditable()
factory TransitionEvent(String type, [Map eventInitDict]) {
  if (eventInitDict != null) {
    var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
    return _blink.BlinkTransitionEvent.instance
        .constructorCallback_2_(type, eventInitDict_1);
  }
  return _blink.BlinkTransitionEvent.instance.constructorCallback_1_(type);
}