RTCIdentityProviderGlobalScope looks wrong

[dontcallmedom]

Initially raised by @annevk at w3c/webrtc-pc#1627

I have some questions/remarks about this global:

1. Is this implemented somewhere?
2. You don't define the name of the global, you just use it in Exposed. That doesn't work. You need something like Global=(Worker,RTCIdentityProviderGlobalScope).
3. Is BroadcastChannel exposed in this global? (Yes, if you need to add Worker which I think you do unless inheriting from WorkerGlobalScope was a mistake.)
4. If so, in what agent cluster does this global find itself?
5. Are there tests?

[dontcallmedom]

Comment by @annevk

I suspect we'll need to update https://html.spec.whatwg.org/#integration-with-the-javascript-agent-formalism as well to account for this global.