change sourceMappingURL pragma to new //# format

* https://docs.google.com/a/groupon.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit
* https://bugzilla.mozilla.org/show_bug.cgi?id=870361
Merge branch 'new-sourceMappingURL-pragma'