// https://html.spec.whatwg.org/multipage/media.html#texttracklist
[Exposed=Window]
interface TextTrackList : EventTarget {
    readonly attribute unsigned long length;
    getter TextTrack (unsigned long index);
    TextTrack? getTrackById(DOMString id);

    attribute EventHandler onchange;
    attribute EventHandler onaddtrack;
    attribute EventHandler onremovetrack;
};
