Implement <video controls> dodging for text track layout

This is a follow-up to "Separate the text track container from the media
controls": https://codereview.chromium.org/949203002/

Previously, we got this behavior for free because the text track
container was part of the media controls.

BUG=448795

Review URL: https://codereview.chromium.org/1018593004

git-svn-id: svn://svn.chromium.org/blink/trunk@192281 bbb929c8-8fbe-4397-9dbb-9b2b20218538
14 files changed
tree: ad68acf03e10cbb8e724726306a6ff6d27502b07
  1. third_party/