anchor.diff:      var instanceIndex = 0;
       _debugMonitor('Class $name Instance=$instanceIndex');
       for (final ObjectReference objRef
  -        in classRef.children as Iterable<ObjectReference>) {
  +        in classRef.children.cast<ObjectReference>()) {
         final fields = objRef.instance.getFields();
         // Root __FIELDS__ is a container for children, the children
         // are added, later, to a treenode - if the treenode should
  
positive.code: 
        final ExternalReferences externals = library as ExternalReferences;
        for (final ExternalReference external
            in externals.children as Iterable<ExternalReference>) {
          assert(external.isExternal);
  
          final liveExternal = external.liveExternal;
          final size = liveExternal.externalProperty.externalSize;
          final liveElement = liveExternal.live;
  
negative.code:       result['externals'] = externalsToAnalyze;
      } else if (library.isFiltered) {
        final filtersToAnalyze = <ClassReference>[];
        for (final Reference libraryRef in library.children) {
          for (final ClassReference classRef
              in libraryRef.children.cast<ClassReference>()) {
            final HeapGraphClassLive liveClass = classRef.actualClass!;
            if (_classMatcher(liveClass)) {
              filtersToAnalyze.add(classRef);
  