anchor.diff:  }
   
   class _ForInData {
  -  static const String tag = '_ForInData';
  -
     final ir.DartType iterableType;
     final ir.DartType iteratorType;
     final ClassRelation iteratorClassRelation;
  
positive.code: }
  
  class _ConstInstantiation {
    static const String tag = '_ConstInstantiation';
  
    final ir.Class cls;
    final List<ir.DartType> typeArguments;
    final ir.LibraryDependency import;
  
    _ConstInstantiation(this.cls, this.typeArguments, this.import);
  
    factory _ConstInstantiation.fromDataSource(DataSource source) {
      source.begin(tag);
      ir.Class cls = source.readClassNode();
      List<ir.DartType> typeArguments = source.readDartTypeNodes();
      ir.LibraryDependency import = source.readLibraryDependencyNodeOrNull();
      source.end(tag);
      return new _ConstInstantiation(cls, typeArguments, import);
    }
  
    void toDataSink(DataSink sink) {
      sink.begin(tag);
      sink.writeClassNode(cls);
      sink.writeDartTypeNodes(typeArguments);
      sink.writeLibraryDependencyNodeOrNull(import);
      sink.end(tag);
    }
  }
  
  enum _Feature {
  
negative.code: 
    _ForInData(this.iterableType, this.iteratorType, this.iteratorClassRelation,
        {this.isAsync});
  }
  