Re-add YouTubePluginReplacement, removed in r285252
Created attachment 453174 [details] Patch
<rdar://problem/89148022>
EWS is all red.
Created attachment 453220 [details] patch
Created attachment 453224 [details] Patch
Committed r290519 (247802@main): <https://commits.webkit.org/247802@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 453224 [details].