Having the ability to write your plugins with ES2015 syntax is nice but
it is missing a large part of the ES2015 spec. Since not all browsers
support this a polyfill is offered.
So far it is IE10 which holds the need for the polyfill. This tiddler
offers a simple how to on adding the babel-polyfill to your TiddlyWiki.
NOTE: This how to would be obsolete if a proper ES2015 polyfill was part
of the official plugins offered in core. (Want a pull request?)