anchor.diff:        listNone(
           typeParameterTypeNone(T),
         ),
  -      strT0: 'List<T>, T & int?',
  -      strT1: 'List<T>',
  +      strT0: 'List<T>, T extends Object?, T & int?',
  +      strT1: 'List<T>, T extends Object?',
       );
     }
   
  
positive.code:     isSubtype(
        type,
        type,
        strT0: 'T?, T & int?',
        strT1: 'T?, T & int?',
      );
    }
  
  
negative.code:         promoteTypeParameter(T, numNone),
        ),
        strT0: 'Null?',
        strT1: 'T, T extends Object, T & num',
      );
    }
  
  