When we parse src for @font-face, CSS-wide keywords are not valid for local(). In case they are the only keywords being input for local, CSSPropertyParserHelpers::concatenateFamilyName will produce a null String, but we won't invalidate the CSSValue for that case.
<rdar://problem/104028095>
Pull request: https://github.com/WebKit/WebKit/pull/8396
Committed 258695@main (1940d518c650): <https://commits.webkit.org/258695@main> Reviewed commits have been landed. Closing PR #8396 and removing active labels.