constructor (type, eventInitDict = {}) {
    if (type === kConstruct) {
      super(arguments[1], arguments[2])
      webidl.util.markAsUncloneable(this)
      return
    }

    const prefix = 'MessageEvent constructor'
    webidl.argumentLengthCheck(arguments, 1, prefix)

    type = webidl.converters.DOMString(type, prefix, 'type')
    eventInitDict = webidl.converters.MessageEventInit(eventInitDict, prefix, 'eventInitDict')

    super(type, eventInitDict)

    this.#eventInit = eventInitDict
    webidl.util.markAsUncloneable(this)
  }
@see https://html.spec.whatwg.org/multipage/comms.html#messageevent