Upstream the below tests from media/track/ to wpt
1. track-webvtt-tc001-utf8.html
2. track-webvtt-tc002-bom.html
3. track-webvtt-tc003-newlines.html
4. track-webvtt-tc004-magic-header.html
5. track-webvtt-tc005-header-comment.html
Bug: 782555
Change-Id: I9d62a7bafbe2a739b6a3046119c023413b900c28
Reviewed-on: https://chromium-review.googlesource.com/814034
Commit-Queue: srirama chandra sekhar <[email protected]>
Reviewed-by: Fredrik Söderquist <[email protected]>
Cr-Commit-Position: refs/heads/master@{#522715}
