[Web Animations] Ensure all timelines are detached from their document
Created attachment 389951 [details] Patch
<rdar://problem/59210306>
Comment on attachment 389951 [details] Patch Noting that I am aware writing a test for this is difficult :)
Comment on attachment 389951 [details] Patch Clearing flags on attachment: 389951 Committed r255953: <https://trac.webkit.org/changeset/255953>
All reviewed patches have been landed. Closing bug.
It looks like the changes here broke imported/w3c/web-platform-tests/web-animations/timing-model/timelines/update-and-send-events.html Tracked in https://bugs.webkit.org/show_bug.cgi?id=207342