Minificated version doesn't support textTracks

[salmazov]

If I use video.js with subtitles ->
Uncaught TypeError: Object [object Object] has no method 'textTracks'

If I use dev-version - all is okey.

[mmcc]

The textTracks method isn't exported yet, which is why it works in the development version but not the minified, production version. It should come soon, as there's already a pull request waiting: #815.