Why wouldn't they, TypeScript does nothing to improve JS performance, faster start-up or iteration times, optimal tree-shaking, etc, it just makes it worse.

Dart is also focused on improving the state of web development with Web Components http://www.dartlang.org/articles/web-ui/ - fixing the DOM with a holistic and consistent API: http://www.dartlang.org/articles/improving-the-dom/ - and providing a single unified abstraction for classes and IO providing much better composability than the fragmentation seen in JS.

Typescript is a superset of JavaScript, while Dart separate language that comes with a dart2js compiler. Not really the same.

More so, Dart has it's own VM.

As if TypeScript ever got anywhere?

Dart already has some small traction and it's not even 1.0 yet -- they just froze the core library APIs.

So, not only they are "still working on it", they have not even released it properly yet.

Not to mention it has totally different goals related to TypeScript (TS = tooling, Dart = performance, language design).

TypeScript has almost no buzz, interest or excitement surrounding it that I can detect, which is sad because I think it's a good effort and great tool. I would appreciate it, if someone could point me to an active and growing TypeScript community.

As for TypeScript tracking ES6, I just watched "Kit Cambridge, "EcmaScript Next: The Subtleties of ES 6" at W3Conf 2013" http://www.youtube.com/watch?v=Dt0f2XdvriQ and am really kind of stunned at how much I hate ES6 now, when before I knew nothing about it.

Dart hits the sweet spot for me.