This property is only ever used by layout tests, not VoiceOver.
<rdar://problem/106909555>
Created attachment 465502 [details] Patch
Created attachment 465503 [details] Patch
Committed 261856@main (81f3db0a48f4): <https://commits.webkit.org/261856@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 465503 [details].