Media Capabilities: update Blink implementation and WPT to match latest spec changes.

Changes are:
- s/type/contentType/ in {Audio/Video}Configuration;
- add [SameObject] to partial Navigator interfaces;
- rename "MediaSource" enum entry to "media-source".

This is also adding more tests for checks of valid
MediaConfiguration.type when running query().

BUG=690380
R=chcunningham@chromium.org

Review-Url: https://codereview.chromium.org/2706093002
Cr-Commit-Position: refs/heads/master@{#451669}
6 files changed