Pushing merged commits to the PR branch should close the pull request, but if it does not, we should explicitly close the pull request.
<rdar://problem/91434587>
Pull request: https://github.com/WebKit/WebKit/pull/260
Committed r292555 (249393@main): <https://commits.webkit.org/249393@main> Reviewed commits have been landed. Closing #260 and removing active labels.