In particular, it becomes [attr], which is the same thing as [|attr], since the default namespace doesn't apply to attribute selectors.
Comment on attachment 407227 [details] [diff] [review] Fix >+ NS_ASSERTION(prefixAtom, >+ "How did we end up with a namespace if the prefix " >+ "is unknown?"); Maybe worth commenting that a non-none namespace on attributes can't have come from the default, since the default doesn't apply? >diff --git a/layout/style/test/test_namespace_rule.html b/layout/style/test/test_namespace_rule.html Did you test that some of the serialize-and-rematch tests failed without the patch? (Did any others fail without it?) r=dbaron
> Did you test that some of the serialize-and-rematch tests failed without the > patch? Yes, precisely. The two [*|foo] tests failed serialize-and-rematch. > (Did any others fail without it?) No. Will add the comment.
Pushed http://hg.mozilla.org/mozilla-central/rev/6af13824b513 with the comment added.