Missing tasks in parallel steps in Media Capture and Streams

[dontcallmedom-bot]

While crawling Media Capture and Streams, the following algorithms fire an event, or resolve or reject a Promise, within a step that runs in parallel without first queuing a task:

• The MediaDevices/enumerateDevices() algorithm resolves/rejects a promise directly in a step that runs in parallel
• The MediaDevices/getUserMedia() algorithm resolves/rejects a promise directly in a step that runs in parallel

See Dealing with the event loop in the HTML specification for guidance on how to deal with algorithm sections that run in parallel.

_{Cc @dontcallmedom @tidoust}

_{This issue was detected and reported semi-automatically by Strudy based on data collected in webref.}