I'm using the Firefox add-on "Deutsches Wörterbuch 2.0.2" which is based, according to the about-section, on igerman98.
It is full of errors of the form Strasse instead of Straße, Grösse instead of Größe and so on.
I tried to find the dictionary on disk without success
grep "^Stra" /home/stefan/.mozilla/firefox/kv88xfop.default/extensions/de-DE@dictionaries.addons.mozilla.org/dictionaries/de-DE.dic
leads to right form,
grep "^Strasse" $(locate de-DE)
grep "^Strasse" $(locate german)
don't yield any results.
More interesting than finding the erroneous data would be a a corrected dictionary, or another solution.
Of course I can add over time the right spelling to the user extension, but this will not remove the wrong one (which are only right for de-CH, where ß isn't used).
Note, that this is not a case of old and new spelling. Straße isn't pronounced like Strapse with a short vocal.
I'm using Firefox 3.6.24 on Xubuntu 10.04 with "Deutsches Wörterbuch 2.0.2" add-on, according to the about-box based on a dictionary called igerman98 from 20091006.