Dart int_enum does not compile
```dart
cases/int_enum.dart:6:7: Error: 'RED' is already declared in this scope.
  var RED = auto();
      ^^^
cases/int_enum.dart:2:7: Context: Previous declaration of 'RED'.
  ST0 RED;
      ^^^
cases/int_enum.dart:7:7: Error: 'GREEN' is already declared in this scope.
  var GREEN = auto();
      ^^^^^
cases/int_enum.dart:3:7: Context: Previous declaration of 'GREEN'.
  ST1 GREEN;
      ^^^^^
cases/int_enum.dart:8:7: Error: 'BLUE' is already declared in this scope.
  var BLUE = auto();
      ^^^^
cases/int_enum.dart:4:7: Context: Previous declaration of 'BLUE'.
  ST2 BLUE;
      ^^^^
cases/int_enum.dart:16:7: Error: 'R' is already declared in this scope.
  int R = 1;
      ^
cases/int_enum.dart:12:7: Context: Previous declaration of 'R'.
  ST0 R;
      ^
cases/int_enum.dart:17:7: Error: 'W' is already declared in this scope.
  int W = 2;
      ^
cases/int_enum.dart:13:7: Context: Previous declaration of 'W'.
  ST1 W;
      ^
```