Fixing bug on minification

Hey, I do my own minification and chart.js broke on minification. Solving the JSLint errors fixed it right up. 

![Screen Shot 2013-03-19 at Mar 19 11 37 27 AM](https://f.cloud.github.com/assets/44229/277368/1e71ec22-90c4-11e2-806d-881b1b3c8811.png)