Tiny optimization: every time AXPostNotificationWithUserInfo is called, it checks associatedPluginParent, which currently goes to the main thread. Since it's almost always nil unless we happen to be on a PDF element, associatedPluginParent should check the isolated object without going to the main thread.
<rdar://problem/118898537>
Created attachment 468792 [details] Patch
Committed 271258@main (7db75daadf99): <https://commits.webkit.org/271258@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 468792 [details].