The patch from bug 210341 caused a regression in the test mentioned in the summary. The test tries to change the media type and codecs of a SourceBuffer on the fly. That operation is unsupported in glib ports, so there is a custom expectation file that expects failures on the transitions between supported types. Bug 210341 adds audio/mpeg (without container) as a new supported format, so new "failures" appear in the test. An unreviewed patch adding expectations for those new failures is going to be added in this bug.
Created attachment 436495 [details] Patch
Committed r281622 (240978@main): <https://commits.webkit.org/240978@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 436495 [details].
<rdar://problem/82386055>