It's a bit confusing, but the bool value returned by paint methods in RenderTheme means whether the appearance is supported or not, so we should return true when not supported (so we didn't paint anything) and false when supported (so we actually painted the theme part).
Created attachment 268772 [details]
Comment on attachment 268772 [details]
Watch the bots....
Committed r194955: <http://trac.webkit.org/changeset/194955>