When we fail to validate a pull request, we should comment on and block that pull request from merge-queue until the issue is resolved.
<rdar://problem/91451392>
Pull request: https://github.com/WebKit/WebKit/pull/264
Committed r292605 (249437@main): <https://commits.webkit.org/249437@main> Reviewed commits have been landed. Closing PR #264 and removing active labels.