audit or disable Apple HLS implementation on Android

As of Firefox 59, Apple's HTTPS Live Streaming (HLS) protocol is supported on Android for both audio and video. We should audit this or at least look at how it is implemented, and possible disable it. Mozilla says: "There is not currently any plan to implement it on Firefox Desktop." See: ​https://bugzilla.mozilla.org/show_bug.cgi?id=577084