merge_pr_8646
Upstream the below tests from media/track/ to wpt 1. track-webvtt-tc011-blank-lines.html 2. track-webvtt-tc013-settings.html 3. track-webvtt-tc014-alignment.html 4. track-webvtt-tc015-positioning.html Bug: 782555 Change-Id: Ie428584d1447fe22ceab45812ee72618fb92bad4 Reviewed-on: https://chromium-review.googlesource.com/818885 Reviewed-by: Fredrik Söderquist <[email protected]> Commit-Queue: srirama chandra sekhar <[email protected]> Cr-Commit-Position: refs/heads/master@{#523066}