anchor.diff:  import '../type_test_helper.dart';
   
   const List<FunctionTypeData> existentialTypeData = const <FunctionTypeData>[
  -  // TODO(johnniwinther): Test generic bounds when #31531 is fixed.
     const FunctionTypeData('void', 'F1', '<T>(T t)'),
     const FunctionTypeData('void', 'F2', '<S>(S s)'),
     const FunctionTypeData('void', 'F3', '<U, V>(U u, V v)'),
  
positive.code:     testToString(F8, '#A Function<#A extends num>(#A)');
      testToString(F9, 'void Function<#A extends #B,#B>(#A,#B)');
      testToString(F10, 'void Function<#A extends #B,#B>(#A,#B)');
  
      testBounds(F1, [Object_]);
      testBounds(F2, [Object_]);
  
negative.code:     InterfaceType int_ = env['int'];
      InterfaceType C1 = instantiate(env.getClass('C1'), []);
      InterfaceType C2 = instantiate(env.getClass('C2'), []);
      ClassEntity C3 = env.getClass('C3');
      InterfaceType C4 = instantiate(env.getClass('C4'), []);
      FunctionType F1 = env.getFieldType('F1');
      FunctionType F2 = env.getFieldType('F2');
      FunctionType F3 = env.getFieldType('F3');
  