Also, some small help on how to reset gfx.xrender.enabled to true to work around it: look in ~/.mozilla/firefox/<hashcode>.default/prefs.js for the same settings that can be configured via about:config. (It may not be trivial to everyone how to do this when Firefox itself is not functional due to the error.)
I can confirm the bug Jaap Woldringh mentioned.
Also, some small help on how to reset gfx.xrender.enabled to true to work around it: look in ~/.mozilla/ firefox/ <hashcode> .default/ prefs.js for the same settings that can be configured via about:config. (It may not be trivial to everyone how to do this when Firefox itself is not functional due to the error.)