They're planning to use AtScript to transpile to ES6 and Dart by extending the ES6 transpiler called Traceur (source: https://docs.google.com/a/google.com/docum

They're planning to use AtScript to transpile to ES6 and Dart by extending the ES6 transpiler called Traceur (source: https://docs.google.com/a/google.com/document/d/11YUzC-1d0V1-Q3V0fQ7KSit97HnZoKVygDxpWzEYW0U/edit https://docs.google.com/a/google.com/document/d/11YUzC-1d0V1...). The basic issue for Angular is they'd like to support users of ES5, ES6, and Dart with the same code base. That's currently a bit hard to do with a Dart code base (although a lot of us want to see that get better!) disclaimer: I've worked on the Dart team and on the Traceur compiler in the past too. So I'm definitely not unbiased on these topics :)