We need to implement the parsing and the data model for the at-rule @font-feature-values. https://drafts.csswg.org/css-fonts-4/#font-display-font-feature-values
<rdar://problem/100830599>
Pull request: https://github.com/WebKit/WebKit/pull/5256
Committed 255677@main (4303ed343b77): <https://commits.webkit.org/255677@main> Reviewed commits have been landed. Closing PR #5256 and removing active labels.