Referencing a client-side image map declared with id attribute doesn’t work in text/html (usemap)
It took only 10 years to fix it. Haven’t looked at the fix yet. I only noticed this bug in 2007 and filed a duplicate.
https://bugzilla.mozilla.org/show_bug.cgi?id=389065
Here are the details https://bugzilla.mozilla.org/show_bug.cgi?id=109445