As of September 2016, new code is expected to be written in ES6 and transpiled down to ES5 for production. See ES6 Learning. At the time of this articles writing, support for the language_out Closure compiler feature is still pending in Goro jscomp. See cl/129027470
TypeScript Editor plugins are thin shims between an editor's extension points and the compiler API that make a developer's life easy and increase the productivity.