[webvtt] Pull Request: Clarify line cue setting specification.

silviapfeiffer has just submitted a new pull request for https://github.com/w3c/webvtt:

== Clarify line cue setting specification. ==
Closes #382 

See https://github.com/w3c/webvtt/pull/399

Received on Saturday, 28 October 2017 05:45:17 UTC