issue-17 | issue-18 | Enable window-crop using 0 offsets + syntax fix fo...

...r ES3
Fix for:
* https://github.com/Wikia/vignette-js/issues/18
* https://github.com/Wikia/vignette-js/issues/17
Thanks! Fixed: https://github.com/Wikia/vignette-js/commit/50cfaed6322a55bcdf736143b1dcbb9074c306be