Fix #1162: MediaStream to continue when context is closed

[rtoy]

When a context is closed any MediaStreams or HTMLMediaElements are
effectively disconnected from the context and continue as if they were
never connected.

[rtoy]

PTAL. Not sure about the most effective way to state what we want.

[padenot]

This means that if AudioContext.close is called, the HTMLMediaElement will start outputing audio to the speakers again, if it was captured with AudioContext.createMediaElementSource. The alternative is to have the frames dropped for ever.

If authors want more flexibility, they can use HTMLMediaelement.captureStream instead. This allows controlling everything manually.

Also it's a bit unclear what connect and disconnect mean, but I think agreeing on the behaviour is more important.

fwiw, https://w3c.github.io/mediacapture-fromelement/#dom-htmlmediaelement-capturestream() has language elements we could have a look at when drafting the spec for createMediaElementSource.

[WofWca]

Not an expert, but tbh this makes AudioContext.createMediaElementSource() look straight up inferior to HTMLMediaElement.captureStream().