Player fails without MediaCapabilities polyfill since v3.2.1

[joeyparrish]

Have you read the FAQ and checked for duplicate open issues?
Yes

What version of Shaka Player are you using?
v3.2.1, v3.2.2, v3.3.0

Can you reproduce the issue with our latest release version?
yes

Can you reproduce the issue with the latest code from master?
yes

Are you using the demo app or your own custom app?
custom

If custom app, can you reproduce the issue using our demo app?
N/A: demo app always installs polyfills

What browser and OS are you using?
any

For embedded devices (smart TVs, etc.), what model and firmware version are you using?
N/A

What are the manifest and license server URIs?

Any

What configuration are you using? What is the output of player.getConfiguration()?

N/A

What did you do?

If polyfills are not installed (or if the MediaCapabilities polyfill specifically is not installed), playback fails with CONTENT_UNSUPPORTED_BY_BROWSER. This is because the polyfill creates a workaround for #3530 at window.shakaMediaCapabilities, and the rest of the code expects that to always exist.

What did you expect to happen?
On platforms that have all the necessary APIs, polyfills should not be required.

What actually happened?

Without installing at least this one polyfill, Shaka Player v3.2.1, v3.2.2, and v3.3.0 are unusable.

See also #3696