CSSVariableReferenceValue does not forward declare or include the required classes.
Pull request: https://github.com/WebKit/WebKit/pull/8378
Committed 258637@main (2a9bdc4807e9): <https://commits.webkit.org/258637@main> Reviewed commits have been landed. Closing PR #8378 and removing active labels.
<rdar://problem/104008058>