anchor.diff:          const Visit(VisitKind.VISIT_SUPER_FIELD_SETTER_COMPOUND,
               getter: 'field(A#a)', setter: 'setter(B#a)',
               operator: '+=', rhs: '42')),
  -    // TODO(johnniwinther): Enable this when dart2js supports shadow setters.
  -    /*const Test.clazz(
  +    const Test.clazz(
           '''
           class A {
             var a;
  
positive.code:         const Visit(VisitKind.VISIT_SUPER_FIELD_SETTER_SET_IF_NULL,
              getter: 'field(A#a)', setter: 'setter(B#a)',
              rhs: '42')),
      // TODO(johnniwinther): Enable this when dart2js supports shadow setters.
      /*const Test.clazz(
          '''
          class A {
            var a;
  
negative.code:           m() => super.a += 42;
          }
          ''',
          // TODO(johnniwinther): Change this to
          // [VISIT_SUPER_FIELD_FIELD_COMPOUND] when dart2js supports shadow
          // setters.
          const Visit(VisitKind.VISIT_SUPER_FINAL_FIELD_COMPOUND,
              element: 'field(B#a)',
              operator: '+=', rhs: '42')),
      const Test.clazz(
          '''
          class B {
  