Atom uses CoffeeScript, but Nuclide[0], Facebook's suite of packages for Atom, uses ES6/7 (including async/await) via Babel. The transpilation and caching of transpiled sources is done in the nuclide-node-transpiler[1] package.

[0] https://github.com/facebook/nuclide

[1] https://github.com/facebook/nuclide/tree/master/pkg/nuclide/...