Support HTTPFallback when appropriate.
<rdar://problem/102911054>
Pull request: https://github.com/WebKit/WebKit/pull/7161
Pull request: https://github.com/webkit/WebKit/pull/7161
Committed 260213@main (6660f0c6e9c9): <https://commits.webkit.org/260213@main> Reviewed commits have been landed. Closing PR #7161 and removing active labels.