It landed with the MWC page last week.

On any page in need of text strings for scripts, add each string as a data attribute in {% block string_data %}. They get appended to a hidden element in the base template and are pulled into an array in global.js.

For reference:
https://github.com/mozilla/bedrock/blob/master/apps/firefox/templates/firefox/partners/landing.html#L14
https://github.com/mozilla/bedrock/blob/master/media/js/global.js#L92
https://github.com/mozilla/bedrock/blob/master/media/js/partners.js#L13

Full credit to @Osmose; it's his trick, I merely pasted.