anchor.diff:  
     @override
     void visitFunctionType(FunctionType type) {
  +    functionTypeParameters.addAll(type.typeFormals);
       for (var typeParameter in type.typeFormals) {
         var bound = typeParameter.bound;
         if (bound != null) {
  
positive.code:         promoteTypeParameter(T, dynamicNone),
        ),
        strT0: 'dynamic',
        strT1: 'T, T & dynamic',
      );
    }
  
  
negative.code:       neverNone,
        typeParameterTypeNone(T),
        strT0: 'Never',
        strT1: 'T, T extends Object?',
      );
    }
  
  