https://drafts.csswg.org/css-align-3/#baseline-export https://drafts.csswg.org/css-writing-modes-4/#line-under The "line under" edge should be item's block start edge in this scenario
<rdar://problem/117273063>
Pull request: https://github.com/WebKit/WebKit/pull/19356
Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/42671
Committed 269668@main (bc94fc496ea9): <https://commits.webkit.org/269668@main> Reviewed commits have been landed. Closing PR #19356 and removing active labels.