style(dart): Format with dartfmt v0.2.0

Format all pure Dart code with package:dart_style v0.2.0

Command:
```
find -type f -name "*.dart" | xargs dartformat -w
```

modules/angular2/src/facade/async.dart

@@ -46,6 +46,7 @@ class TimerWrapper {
       fn();
     });
   }
+
   static void clearInterval(Timer timer) {
     timer.cancel();
   }