>>> https://github.com/dart-lang/dart_style/issues/14
class A {
  final Map x;
  A() : x = {
        // comment
        'foo': 1,
        'bar': 2,
      };
}
<<<
class A {
  final Map x;
  A() : x = {
        // comment
        'foo': 1,
        'bar': 2,
      };
}