The last subtest of css/css-backgrounds/parsing/background-shorthand-serialization.html is failing in STP 164 when it used to pass in STP 163: https://wpt.fyi/results/css/css-backgrounds/parsing/background-shorthand-serialization.html?label=master&label=experimental&product=safari-163%20preview&product=safari-164%20preview&view=subtest We need to find out if this is a bug in WebKit or an issue with the test. We should also take the opportunity to import this test so this could be caught with EWS going forward.
The issue here is "transparent" vs. "none" for the default background which can be specified many ways, including "background: transparent" and "background: none".
Tim filed this https://github.com/w3c/csswg-drafts/issues/8496
We can just assume that we want this to serialize as "none" and fix it right away rather than waiting for the issues to be resolved. The fix is really easy: 1) Move "background-color" to the end of the list of longhands in CSSProperties.json for "background". 2) Rebase all the tests that change results.
<rdar://problem/106208628>
Pull request: https://github.com/WebKit/WebKit/pull/11087
Committed 261250@main (bec59bdd1e26): <https://commits.webkit.org/261250@main> Reviewed commits have been landed. Closing PR #11087 and removing active labels.