revert to original stack trace in case of failure

So it turns out this function fails sometimes. I encoutnered it while
converting urbanairship's js tests from drive to tape + jsdom-eval + sinon. It
looks like one of these calls: https://github.com/AWinterman/jsdom-eval/blob/master/index.js#L42-L43
involves a method lookup against undefined. I'm not sure under which conditions
this happens, and can continue to investigate if needed.
fix typo
Merge pull request #3 from AWinterman/master

revert to original stack trace in case of failure