There are a few calls in WTR::AccessibilityUIElement into the Mac WebAccessibilityObjectWrapper API that need to be dispatched to the AX thread for testing purposes.
<rdar://problem/94260093>
Created attachment 459948 [details] Patch
Looks good to me.
Committed r295125 (251216@main): <https://commits.webkit.org/251216@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 459948 [details].