MediaStream Recording spec activity

Inspired by the merry feelings coming along in these dates, there has been
a flurry of cleanup in media-recording-land. A few issues
<https://github.com/w3c/mediacapture-record/issues?q=is%3Aissue+sort%3Aupdated-desc>
have been addressed in a ToT draft (see here
<https://rawgit.com/w3c/mediacapture-record/master/MediaRecorder.html> for
the latest latest canary-like spec), where some other more interesting
points are in the making:

- it was proposed to change static DOMString canRecordMimeType() with bool
isTypeSupported()[1]; this should be straightforward since Gecko does not
implement it and I think is not massively popular in Blink either. So I
landed it, please speak up if this surprises you.

- change the options mimeType to a dictionary [2]. Basically this takes in
Gecko's implementation.

- simplify the ErrorEvent [3], basically removing any specific MR error
event mechanics and instead having a simple ErrorEvent (eventually, with
the appropriate information in a "message" field). This is somehow very
similar to Gecko implementation
<https://github.com/mozilla/gecko-dev/blob/master/dom/webidl/RecordErrorEvent.webidl>
if
I understand it correctly.



[1]  issue: https://github.com/w3c/mediacapture-record/issues/10 .
[2] issue: https://github.com/w3c/mediacapture-record/issues/19 and also
https://github.com/w3c/mediacapture-record/issues/20, pull request:
https://github.com/w3c/mediacapture-record/pull/34)
[3] issue: https://github.com/w3c/mediacapture-record/issues/31, pull
request https://github.com/w3c/mediacapture-record/pull/36

-- 

Miguel Casas-Sanchez | Gatopardo del Software | ydog <ydog@google.com> /
mcasas@google.com | +1 (650) 603 1380