The ic-height support is missing for font-size-adjust with two-value syntax. Although there is some ambiguity in the spec [1], Gecko's behavior sounds reasonable so WebKit implements it. [1] https://github.com/w3c/csswg-drafts/issues/8792
<rdar://problem/118142648>
Pull request: https://github.com/WebKit/WebKit/pull/20717