We need to test <length-percentage> custom property interpolation
Pull request: https://github.com/WebKit/WebKit/pull/7697
Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/37530
Committed 257931@main (c0462225cee0): <https://commits.webkit.org/257931@main> Reviewed commits have been landed. Closing PR #7697 and removing active labels.
<rdar://problem/103406885>