AX: Make 6 layout tests async so they can pass in ITM
<rdar://problem/101191194>
Created attachment 462996 [details] Patch
Created attachment 463010 [details] Patch
Committed 255599@main (33f7c1b9c1e2): <https://commits.webkit.org/255599@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 463010 [details].