Clearfix output should use double colon notation

[pdincubus]

The output for the native Clearfix outputs a :after which should be ::after as per CSS3 spec.

Browser support is IE9+, FF 3.5+, Edge, Safari and Chrome so should not cause issues for anyone supporting current browser usage. Maybe needs an 'Old IE' fallback option to output the :after version too to give choice?

[pdincubus]

I've made the change to the postcss-clearfix repo and made a pull request.

[madeleineostoja]

Yep that was done because postcss-clearfix used to have a legacy option, but it was removed a few versions ago. Happy to merge that PR.