If a format is unsupported but a valid keyword, it should still be a parsed. The unsupported font format should not be loaded though. See https://github.com/w3c/csswg-drafts/issues/8793
<rdar://problem/112135869>
Pull request: https://github.com/WebKit/WebKit/pull/15819
Committed 266043@main (b2a00a22e3c4): <https://commits.webkit.org/266043@main> Reviewed commits have been landed. Closing PR #15819 and removing active labels.