`Clear-Site-Data: "cache"` HTTP header should clear the back/forward cache.
Pull request: https://github.com/WebKit/WebKit/pull/4617
Committed 254798@main (5e99c8f621c3): <https://commits.webkit.org/254798@main> Reviewed commits have been landed. Closing PR #4617 and removing active labels.
<rdar://problem/105102844>