Turn on Clear-Site-Data HTTP header support in modern WebKit now that its implementation is complete and we've addressed all known issues.
Pull request: https://github.com/WebKit/WebKit/pull/9759
Committed 259970@main (43c15c5af20a): <https://commits.webkit.org/259970@main> Reviewed commits have been landed. Closing PR #9759 and removing active labels.
<rdar://problem/105137603>