The case where the list looses the active descendant attribute is failing in ITM.
<rdar://problem/110544948>
Created attachment 466655 [details] Patch
Comment on attachment 466655 [details] Patch r+ once compilation errors due to unused value on !ENABLE(ACCESSIBILITY_ISOLATED_TREE) platforms are fixed.
Created attachment 466663 [details] Patch
Committed 265065@main (cbe05390f6ae): <https://commits.webkit.org/265065@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 466663 [details].