[hsivonen]

Your example is not an example of actual Firefox failure mode: If I encode your text as ISO-8859-1 and run chardetng on the bytes, it says ISO-8859-2. It’s generally unlikely that chardetng would misdetect ISO-8859-2 Polish as windows-1252.

When you claim that something isn’t working for you (and it’s completely plausible that you have encountered a case where chardetng doesn’t work for you), it would be polite to post the actual failure and not something that’s not an actual example of failure.