Remove some custom-element tests since they are now available in WPT.
Created attachment 459408 [details] Patch
Comment on attachment 459408 [details] Patch I can confirm they're in: LayoutTests/imported/w3c/web-platform-tests/custom-elements/
Committed r294227 (250585@main): <https://commits.webkit.org/250585@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 459408 [details].
<rdar://problem/93338044>