DEV: Add support for class properties in babel (PR #13189)

This allows us to start using JS classes instead of Ember’s classes.


Error: MiniRacer::RuntimeError: SyntaxError: /discourse/app/lib/lock-on: Decorators are not enabled.

Test failure seems relevant as Riking noted, looks like the order matters:

(in JavaScript If you are using ["@babel/plugin-proposal-decorators", { “legacy”: true }], make sure it comes before@babel/plugin-proposal-class-properties” and enable loose mode, like so:)

It would be great if these lists of Babel plugins were more readable, it’s hard to scan them now for already enabled plugins.

Not a bad suggestion, I’ll follow up.