https://wpt.fyi/results/css/css-transforms/transform-box/fill-box-002.html?label=master&label=experimental&product=chrome&product=firefox&product=safari&aligned&view=interop&q=label%3Ainterop-2021-transforms My likely guess is that we need to recompute the transform when we're finished laying out the children.
<rdar://problem/100647287>
Pull request: https://github.com/WebKit/WebKit/pull/4896
Committed 255060@main (3c6b4ac4654c): <https://commits.webkit.org/255060@main> Reviewed commits have been landed. Closing PR #4896 and removing active labels.