I added HTMLTrackElement to the Mozilla Developer Network (MDN) wiki. I made sure it was technically correct and conformed to formatting standards already set by similar pages on MDN.
The TextTrack object is not defined in MDN. I did not do so because similar attributes are not present in other pages. For example the read only attributes audioTracks, videoTracks, and textTracks, which are not defined in MDN's HTMLMediaElement but are in the specification.