Vendor prefixes

[nsaunders]

I wonder whether vendor prefixes are better addressed as a separate concern by another tool (specifically Autoprefixer), considering the following:

1. CSS output size could be reduced, since Autoprefixer uses Browserslist.
2. Because it's specifically focused on this problem (and, judging by its 20k stars, has more eyes on it), Autoprefixer likely has better coverage.
3. This codebase could be simplified.
4. purescript-css' implementation (lifted from Clay) is...semi-broken?
5. (Perhaps unlike Clay) purescript-css is written in a language that has an easy and convenient JavaScript FFI. 👍

If anyone would miss this functionality, would be significantly inconvenienced by having to use Autoprefixer, or simply has some thoughts to share, please let me know!

[JordanMartinez]

I think this makes sense!