[webrtc-pc] Race condition between createOffer and setIdentityProvider

taylor-b has just created a new issue for https://github.com/w3c/webrtc-pc:

== Race condition between createOffer and setIdentityProvider ==
Suppose an application does:

```
pc.setIdentityProvider(a);
pc.createOffer().then(...);
// Some time later, but before createOffer's promise has resolved:
pc.setIdentityProvider(b);
```

Is there a guarantee which identity provider will be used to generate "a=identity"?

Note that I already tried to fix the `createOffer` race conditions here: https://github.com/w3c/webrtc-pc/pull/875

But this one may still exist.

Please view or discuss this issue at https://github.com/w3c/webrtc-pc/issues/1184 using your GitHub account