Silence Chrome error about interrupted play() requests

[joeyparrish]

Chrome sometimes throws this error in the JS console:

Uncaught (in promise) DOMException: The play() request was interrupted by a call to pause()

This is not a real problem, and this log comes from Chrome, not the app. The error is very confusing to developers, and it often shows up as a red herring in Shaka Player bug reports.

App developers have been complaining about it to Chrome for more than a year now, and although the error appears less often since Chrome 52, it continues to occur in some cases.

Since this error adds no value for us and is confusing for developers, we should silence this error with a polyfill on HTMLMediaElement.prototype.play.

[joeyparrish]

Filed an issue on Chromium to fix at a platform level as well: https://bugs.chromium.org/p/chromium/issues/detail?id=728294

[joeyparrish]

Quickest repro steps for Shaka Player:

1. Open the demo app and the JS console
2. Select any clip (Heliocentrism is shortest)
3. Click "Load"
4. Play the clip to the end
5. Select any other clip
6. Click "Load"

You will see in the console:

Uncaught (in promise) DOMException: The play() request was interrupted by a new load request.

[joeyparrish]

Cherry-picked to v2.1.3.