Since we've moved the browser support stuff into a separate file, I actually don't think we need to create a separate tag for open source and production. The differences here (`SINGLE_MODE` and `ALLOW_SKIP_PREVIEW)` aren't really necessary to override, and in my option not worth having to maintain two tags for.

For `SINGLE_MODE`, I don't think we need this variable at all - checking for the existence of `options['mode']` is good enough. Same goes for `ALLOW_SKIP_PREVIEW`. There isn't anything in the way of saving space - we could just remove both these variables and save even more bytes!