Adding a child to an AccessibilitySlider that has lost its renderer dynamically causes a crash
<rdar://problem/96964601>
Created attachment 460869 [details] Patch
Created attachment 460873 [details] Patch
Committed 252444@main (c30b6646dc63): <https://commits.webkit.org/252444@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 460873 [details].