VideoTrack.language, .kind, and .sourceBuffer are not enabled when ManagedMediaSource is enabled but MediaSource is not.
rdar://116158362
Pull request: https://github.com/WebKit/WebKit/pull/18467
Committed 268711@main (325f73e7161e): <https://commits.webkit.org/268711@main> Reviewed commits have been landed. Closing PR #18467 and removing active labels.