See failures in https://wpt.fyi/results/css/css-grid/parsing/grid-shorthand-valid.html?label=master&label=experimental&product=chrome&product=firefox&product=safari&aligned&view=interop&q=label%3Ainterop-2021-grid
<rdar://problem/99777985>
Pull request: https://github.com/WebKit/WebKit/pull/4648
Committed 254974@main (d6bea689bd25): <https://commits.webkit.org/254974@main> Reviewed commits have been landed. Closing PR #4648 and removing active labels.