We added a feature flag years ago to enable us to A/B test this change and debug site issues. In the years since, the spec and other browsers have aligned on this behavior and we no longer need this flag.
<rdar://problem/102390126>
Pull request: https://github.com/Webkit/WebKit/pull/6533
Committed 257075@main (32f5078653c2): <https://commits.webkit.org/257075@main> Reviewed commits have been landed. Closing PR #6533 and removing active labels.