The test has become flaky after r291998 removed the 1ms minimum for setTimeout, as the test uses various calls to setTimeout with a value of 0, which apparently results in accessibility events not being delivered consistently if a combobox value is programmatically changed and then immediately changed again. Changing the timeout between the two changes to the combobox value back to 1ms fixes the issue.
Created attachment 458573 [details] Patch
Committed r293624 (250130@main): <https://commits.webkit.org/250130@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 458573 [details].
<rdar://problem/92534180>