Firefox 11: https://github.com/jashkenas/backbone/runs/4907194010?check_suite_focus=true

Chrome 26 and 40: https://github.com/jashkenas/backbone/runs/5250001247?check_suite_focus=true#step:6:105

IE 9 and 10: https://github.com/jashkenas/backbone/runs/5250001247?check_suite_focus=true#step:6:182

I have disabled these browsers in the karma.conf-sauce.js for the time being, but getting them to run somehow would be desirable.