code: function MessageEvent (type, eventInitDict) {
    Object.defineProperty(this, 'type', { writable: false, value: type, enumerable: true })
    for (var f in eventInitDict) {
      if (eventInitDict.hasOwnProperty(f)) {
        Object.defineProperty(this, f, { writable: false, value: eventInitDict[f], enumerable: true })
      }
    }
  }
docs: W3C MessageEvent
  
  @see http://www.w3.org/TR/webmessaging/#event-definitions
  @api private