Bugzilla

Hmm, I'm going to un-dupe actually; I think the tests in bug 1841317 are about checking that :first-line skips over grid children when finding the first line (which is a subtle thing), whereas this bug here is about whether or not the first-line applies in a grid item (which is less subtle).

Per bug 1841317 comment 7, I think the failures here are due to an unrelated-to-grid bug; they're accidentally relying on blocks discovering their first-line in a descendant, which doesn't work properly for us right now and is tracked in bug 317081.  We can fix the tests so they don't depend on that; there's separate and more-direct WPT test coverage for this behavior in these other tests at least:
https://wpt.fyi/results/css/css-pseudo/first-line-on-ancestor-block.html
https://wpt.fyi/results/css/css-pseudo/first-line-change-inline-color.html

Hmm, I'm going to un-dupe actually; I think the tests in bug 1841317 are about checking that :first-line skips past grid children when finding the first line (which is a subtle thing), whereas this bug here is about whether or not the first-line applies in a grid item (which is less subtle).

Per bug 1841317 comment 7, I think the failures here are due to an unrelated-to-grid bug; they're accidentally relying on blocks discovering their first-line in a descendant, which doesn't work properly for us right now and is tracked in bug 317081.  We can fix the tests so they don't depend on that; there's separate and more-direct WPT test coverage for this behavior in these other tests at least:
https://wpt.fyi/results/css/css-pseudo/first-line-on-ancestor-block.html
https://wpt.fyi/results/css/css-pseudo/first-line-change-inline-color.html