esc_js for translatable string in the javascripts

As on master branch:
- https://github.com/woothemes/woocommerce/commit/ba923875a20b66292d4b5c2a4f492506cb4a4a99
- https://github.com/woothemes/woocommerce/commit/3f1bca59ccf006480447d24cec7bbdb4cd7619a1