We've compiled a list of some of the language features that are targeted for the M1 release of Dart. We hope this helps you track the features you are interested in. This list is a good way to associate a specific language change to its implementation in the Dart VM, Dart2js, and the Analyzer.
Be sure to star the bugs important to you, and you'll get notifications when the issues are closed.
As always, we really appreciate feedback on the Dart mailing list and Stack Overflow.
(This isn't a complete list, and of course things can change in the future.)