In particular, it becomes [attr], which is the same thing as [|attr], since the default namespace doesn't apply to attribute selectors.
Created attachment 407227 [details] [diff] [review]
Comment on attachment 407227 [details] [diff] [review]
>+ "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?)
> Did you test that some of the serialize-and-rematch tests failed without the
Yes, precisely. The two [*|foo] tests failed serialize-and-rematch.
> (Did any others fail without it?)
Will add the comment.
Pushed http://hg.mozilla.org/mozilla-central/rev/6af13824b513 with the comment added.