#import 
#import 
#import 
// https://html.spec.whatwg.org/multipage/media.html#trackevent
[Exposed=Window, UseNewAKString]
interface TrackEvent : Event {
    constructor(DOMString type, optional TrackEventInit eventInitDict = {});
    // FIXME: Should be: (VideoTrack or AudioTrack or TextTrack)?
    readonly attribute (VideoTrack or AudioTrack)? track;
};
dictionary TrackEventInit : EventInit {
    // FIXME: Should be: (VideoTrack or AudioTrack or TextTrack)?
    (VideoTrack or AudioTrack)? track = null;
};