Enable BroadcastChannel for modern WebKit.
Created attachment 438087 [details] Patch
Comment on attachment 438087 [details] Patch r=me
Committed r282426 (241685@main): <https://commits.webkit.org/241685@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 438087 [details].
<rdar://problem/83123934>