MediaRecorder: update to spec (2/3)

- s/DOMString canRecordMimeType/bool isTypeSupported/, see [1]
- s/mimeType/options dictionary/, related to [2]

Also, updated tests everywhere.

BUG=262211

[1] https://github.com/w3c/mediacapture-record/issues/10
[2] https://github.com/w3c/mediacapture-record/issues/19

Review URL: https://codereview.chromium.org/1507183002

Cr-Commit-Position: refs/heads/master@{#364573}
11 files changed