anchor.diff:          // Class is not interesting.
           continue;
         }
  -      vmService.HeapSnapshotClass c = graph.classes[o.classId - 1];
  +      vmService.HeapSnapshotClass c = o.klass;
         Map<String, List<String>> interests = _interests[c.libraryUri];
         if (interests == null || interests.isEmpty) {
           // Not an object we care about.
  
positive.code:       vmService.HeapSnapshotObject o,
        vmService.HeapSnapshotGraph graph,
        Map<Uri, Map<String, List<String>>> prettyPrints) {
      if (o.classId == 0) {
        return "Class sentinel";
      }
      vmService.HeapSnapshotClass class_ = graph.classes[o.classId - 1];
  
      if (class_.name == "_OneByteString") {
        return '"${o.data}"';
  
negative.code:         new List<bool>.filled(graph.classes.length, false);
      for (int i = 0; i < graph.objects.length; i++) {
        vmService.HeapSnapshotObject o = graph.objects[i];
        if (o.classId <= 0) {
          // Sentinel.
          continue;
        }
  