Localizations no longer work in Firefox and Thunderbird version 10

[Christian Mangin]

After upgrading to Firefox 10, I found that the localizations are no
longer available even though
www/firefox-i18n has also been upgraded to version 10.

The localizations files seem to be properly installed but they are not
recognized by Firefox, i.e. there is no 'Languages' tab in the add-ons
panel.

I also found that Thunderbird had the same problem after the upgrade to
version 10.

--
Christian