Now templates are in core, there is very little reason for Mantle to exist.
For Flow:
- Move the javascripts/templates/handlebars.js file into the Flow repository.
MobileFrontend:
Mantle [after Flow and MobileFrontend changes have been made]
Adding Zero in case this will have any impacts on them.
Once the above are done we should remove the dependency and deprecate the extension for the time being. We can always resurface it if needed.