Fix Qunit.done use to support grunt-contrib-qunit

It was overriding Qunit.done, but that doesn't appear to be necessary and it causes a PhantomJS timeout when using grunt-contrib-qunit. They must be using done() also.
Instead we can just pass the function as an arg as intended.
http://api.qunitjs.com/QUnit.done/

Not really a problem unless you switch to grunt some day.