Closed
Description
With #9695, we upgraded to Babel 6, which was released in 2015. Now, it's 2018, and Babel 7 is out. It's time to upgrade.
Some highlights: It's now a monorepo with scoped packages, supports dynamic configuration in JavaScript, supports TypeScript, and contains a variety of other features and optimizations. See https://babeljs.io/blog/2018/08/27/7.0.0 for details.
