This concerns code that should have been removed years ago, such as support code for Mavericks.
Pull request: https://github.com/WebKit/WebKit/pull/9774
<rdar://problem/105462559>
Pull request: https://github.com/WebKit/WebKit/pull/10586
Committed 260831@main (6aa0efabfa86): <https://commits.webkit.org/260831@main> Reviewed commits have been landed. Closing PR #10586 and removing active labels.