Google on Tuesday has been released new Dart SDK Milestone 4 (v0.4.7 r21548). You can download here. This versions is the fourth milestone now from dartlang.org/tools.
The official changes log for Dark SDK are following:
1- Core, collection, and async libraries are now stable. There will be no more breaking changes to these libraries.
2-Performance improved in both the dart2js compiler and the Dart VM.
3-Dart Editor comes with an all-new analysis engine for faster real-time feedback.
4-Classes can be used as mixins.
Google said, dart2js now generates more efficient code. Compared to the previous M3 release, DeltaBlue runs twice as fast and Richards runs 40% faster. The native Dart VM now runs Richards twice as fast as V8. On DeltaBlue, the VM improved by 22%. Details are available at dartlang.org/performance.