Resolve JS hint errors

Minor touch up so it passes validation
> Is it a bug that PhantomJS behaves differently than the real browsers? I

It looks like there's nothing PhantomJS related going on, because `function(){return this;}()` fails on Chrome too:
```
INFO [launcher]: Starting browser PhantomJS
INFO [launcher]: Starting browser Chrome
INFO [PhantomJS 1.9.8 (Mac OS X)]: Connected on socket VJPW1yo4NNpuoQ5K8UV1 with id 56127288
PhantomJS 1.9.8 (Mac OS X) LOG: 'global is set to:', undefined

PhantomJS 1.9.8 (Mac OS X) ERROR
  TypeError: 'undefined' is not an object (evaluating 'context[name] = definition()')
  at ../dist/lib/csv-js/csv.js:349


INFO [Chrome 39.0.2171 (Mac OS X 10.9.5)]: Connected on socket -i0ws8HGWJAYnKPo8UV2 with id 41686224
Chrome 39.0.2171 (Mac OS X 10.9.5) LOG: 'global is set to:', undefined

Chrome 39.0.2171 (Mac OS X 10.9.5) ERROR
  Uncaught TypeError: Cannot set property 'CSV' of undefined
  at ../dist/lib/csv-js/csv.js:349
```

As I mentioned earlier, with `Function('return this')()` everything works fine.