Clean up asynchronous behavior in some accessibility tests

Clean up asynchronous behavior in some accessibility tests
https://bugs.webkit.org/show_bug.cgi?id=148682

Reviewed by Darin Adler.

* accessibility/mac/removing-textarea-after-edit-crash-expected.txt:
* accessibility/mac/removing-textarea-after-edit-crash.html:
* accessibility/mac/select-element-selection-with-optgroups.html:
* accessibility/mac/selected-rows-table.html:
* accessibility/mac/selection-notification-focus-change.html:
* accessibility/mac/selection-sync-expected.txt:
* accessibility/mac/selection-sync.html:
* accessibility/mac/setting-attributes-is-asynchronous.html:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@189221 268f45cc-cd09-0410-ab3c-d52691b4dbfc