Old IE Remastered

Polyfills Window, HTMLDocument, HTMLElement in old IE
Removes Window.polyfill
Removes html5shiv
Yes, absolutely.  default  = polyfill.js, and any config outside of
variants will be considered part of default.

I've tried to put together some better guidelines on this, see this branch:
https://github.com/Financial-Times/polyfill-service/blob/contributing-guide/CONTRIBUTING.md