anchor.diff:      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');
  
positive.code:     FunctionType F8 = env.getFieldType('F8');
      FunctionType F9 = env.getMemberType('F9');
      FunctionType F10 = env.getClosureType('F10');
  
      List<FunctionType> all = <FunctionType>[
        F1,
  
negative.code:     testBounds(F8, [num_]);
      testBounds(F9, [F9.typeVariables.last, Object_]);
      testBounds(F10, [F10.typeVariables.last, Object_]);
      testBounds(F11, [
        instantiate(C3, [F11.typeVariables.last])
      ]);
      testBounds(F12, [
        instantiate(C3, [F12.typeVariables.last])
      ]);
  
      testInstantiate(F1, [C1], 'void Function(C1)');
      testInstantiate(F2, [C2], 'void Function(C2)');
  