Introduction of BaseAudioContext and broken prototype

Hello all,

I would like to report an issue about the recent breakage in Chromium due
to the newly introduced BaseAudioContext.

I believe this is the spec decision we have made:
https://github.com/WebAudio/web-audio-api/issues/1022
https://github.com/WebAudio/web-audio-api/issues/308#issuecomment-149363285

However, this change caused some issues in several WebAudio libraries that
check the prototype properties on AudioContext with `hasOwnProperty()`
method. For example, this will fail:

AudioContext.prototype.hasOwnProperty('createGain');

1. Is this WG's mistake to overlook this breakage? If so, should we revert
this spec change and have completely separate IDLs for AudioContext and
OfflineAudioContext?
2. If the WG's decision still holds, how do we announce this change to
developers?
3. Paul suggested that we might be able to avoid exposing this and have two
separate classes in the implementation. Is this allowed from the TAG's
perspective?

Thanks.

Best,
Hongchan