Drop non-standard AudioBuffer.gain: - https://www.w3.org/TR/webaudio/#AudioBuffer Blink does not expose this attribute either.
Created attachment 408768 [details] Patch
Committed r267065: <https://trac.webkit.org/changeset/267065> All reviewed patches have been landed. Closing bug and clearing flags on attachment 408768 [details].
<rdar://problem/68893033>