OfflineAudioContext.destination currently always has a number of channels that is 0, no matter the numberOfChannels provided when constructing the OfflineAudioContext. The channel count mode is also "max" instead of "explicit".
Created attachment 406620 [details] Patch
Created attachment 406627 [details] Patch
Committed r265713: <https://trac.webkit.org/changeset/265713> All reviewed patches have been landed. Closing bug and clearing flags on attachment 406627 [details].
<rdar://problem/67103681>