All the hits on Github seem to be either MDN docs or WebKit repository clones. https://github.com/search?q=-webkit-animating-full-screen-transition&type=code&p=1
<rdar://problem/121302758>
Pull request: https://github.com/WebKit/WebKit/pull/23009
Committed 273259@main (8ebf7a9fbf27): <https://commits.webkit.org/273259@main> Reviewed commits have been landed. Closing PR #23009 and removing active labels.
Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/44111