w3c/webvtt — pull request #12 by foolip (2014-01-24 07:17:30+00:00)
Title: Use partial interface to extend TextTrack

https://www.w3.org/Bugs/Public/show_bug.cgi?id=23686

Note that maybe we shouldn't extend TextTrack:
https://www.w3.org/Bugs/Public/show_bug.cgi?id=24380