MessageEvent

void initMessageEvent(
    in DOMString typeArg,
    in boolean canBubbleArg,
    in boolean cancelableArg,
    in DOMString dataArg,
    in DOMString originArg,
    in DOMString lastEventIdArg,
    in DOMWindow sourceArg,
    in MessagePort messagePort); 

readonly attribute DOMString data; 

readonly attribute DOMString lastEventId; 

readonly attribute MessagePort messagePort; 

readonly attribute DOMString origin; 

readonly attribute DOMWindow source;