StageXL: fast and universal 2D rendering engine for HTML5 and Dart 11 years ago
Sneak Peek on a StageXL framework I am working on: http://rockdot.sounddesignz.com/template/
Screen Management + Responsive Layouts + Material Design UI library + Spring Application Context (IoC/DI) + MVC/Commands + Physics + Google API + Facebook API + whatnot.
To kind of prove that the Dart2JS compiler is amazing: What you see comes in 230KiB gzipped.
Also make sure to check out the button to the upper right. If it does magic, you're on WebGL.