anchor.diff:  
     @override
     InterfaceType get streamDynamicType {
  -    _streamDynamicType ??= streamType.instantiate(<DartType>[dynamicType]);
  +    _streamDynamicType ??= InterfaceTypeImpl.explicit(
  +      streamElement,
  +      [dynamicType],
  +      nullabilitySuffix: _nullabilitySuffix,
  +    );
       return _streamDynamicType;
  +  }
  +
  +  ClassElement get streamElement {
  +    return _streamElement ??= _getClassElement(_asyncLibrary, 'Stream');
     }
   
     @override
  
positive.code: 
    @override
    InterfaceType get futureDynamicType {
      _futureDynamicType ??= futureType.instantiate(<DartType>[dynamicType]);
      return _futureDynamicType;
    }
  
    @override
    InterfaceType get futureNullType {
      _futureNullType ??= futureType.instantiate(<DartType>[nullType]);
      return _futureNullType;
    }
  
    @override
    InterfaceType get futureOrNullType {
      _futureOrNullType ??= futureOrType.instantiate(<DartType>[nullType]);
      return _futureOrNullType;
    }
  
  
negative.code:   final NullabilitySuffix _nullabilitySuffix;
    final LibraryElement _coreLibrary;
    final LibraryElement _asyncLibrary;
  
    ClassElement _futureElement;
    ClassElement _futureOrElement;
    ClassElement _iterableElement;
    ClassElement _mapElement;
    ClassElement _streamElement;
  
    InterfaceType _boolType;
    InterfaceType _deprecatedType;
  