Yup, thanks! What's the story for modern browsers that don't yet support those features? Do they both have polyfills?
As I mentioned in the article, libraries and futures aren't exclusive to Dart. It's just that they are here now for Dart and are compiled to JavaScript for all modern browsers.
I think it's telling that the original author didn't use Promises or Modules. Of course he could have, but we should ask, why didn't he?
While a lot of browsers are still lacking pretty much any ES6 support, you can get around this by using Traceur [1] to compile your ES6 javascript down to ES5, and then using the es6-shim [2] for new ES6 libraries (Promise, etc.)
Given that you'll need to compile dart down to JS for it to run on any browser (including chrome), and given that it seems unlikely Mozilla will ever include a dart VM, I'd say that starting to learn ES6 now is probably a better long-term bet than learning dart. Which isn't to say Dart isn't a nice language...
Spec: http://wiki.ecmascript.org/doku.php?id=harmony:modules
1: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...