MSE was added behind an experimental flag for testing reason. Now that Managed Media Source has been shipped, it should be moved back to be an internal flag.
<rdar://problem/110867860>
Pull request: https://github.com/WebKit/WebKit/pull/15035
Committed 265240@main (cb8db9bb084b): <https://commits.webkit.org/265240@main> Reviewed commits have been landed. Closing PR #15035 and removing active labels.