Currently @supports rules are enabled for nightly/aurora versions but not for beta/release versions. Given that the spec is going to CR very soon (and should be by the time current nightly gets to beta), we should enable it for all builds so that we ship it. I don't see any known issues that should block us from doing this. (I don't see any valid issues remaining in bug 780060 or bug 816045.) But I probably ought to check the current test suite submissions.
Created attachment 730335 [details] [diff] [review] Turn on @supports in release builds.
Comment on attachment 730335 [details] [diff] [review] Turn on @supports in release builds. r=me if you're happy with how we fare on any @supports tests we haven't yet imported from the official test suite.
https://hg.mozilla.org/integration/mozilla-inbound/rev/b2f950261473 I still need to go through the tests, though.
Could someone update the realese notes? https://www.mozilla.org/en-US/firefox/22.0beta/releasenotes/
I don't think this belongs in the release notes, but it does belong in developer documentation.
In Opera's tests, we fail at-supports-014, which is incorrect as described here (with patch): http://lists.w3.org/Archives/Public/public-css-testsuite/2013May/0019.html and we fail 4 items in contributors/opera/submitted/css3-conditional/js/001.html . I again think the test is invalid, as described here: http://lists.w3.org/Archives/Public/public-css-testsuite/2013May/0020.html