anchor.diff:    int get retainedSize => _graph._retainedSizes[_id];
     ObjectVertex get dominator => new ObjectVertex._(_graph._doms[_id], _graph);
   
  -  int get shallowSize {
  -    var stream = new ReadStream(_graph._chunks);
  -    stream.position = _graph._positions[_id];
  -    stream.skipUnsigned(); // addr
  -    stream.readUnsigned(); // shallowSize
  -    return stream.clampedUint32;
  -  }
  -
  -  int get vmCid {
  -    var stream = new ReadStream(_graph._chunks);
  -    stream.position = _graph._positions[_id];
  -    stream.skipUnsigned(); // addr
  -    stream.skipUnsigned(); // shallowSize
  -    stream.readUnsigned(); // cid
  -    return stream.clampedUint32;
  -  }
  +  int get shallowSize => _graph._shallowSizes[_id];
  +  int get vmCid => _graph._cids[_id];
   
     get successors => new _SuccessorsIterable(_graph, _id);
   
  
positive.code:     }
    }
  
    bool get isZero {
      return (high == 0) && (mid == 0) && (low == 0);
    }
  
negative.code: 
      // Fill predecessors array.
      for (var i = 1; i <= N; i++) {
        var startSuccIndex = firstSuccs[i];
        var limitSuccIndex = firstSuccs[i + 1];
        for (var succIndex = startSuccIndex;
             succIndex < limitSuccIndex;
             succIndex++) {
          var succId = succs[succIndex];
          var predIndex = nextPreds[succId]++;
          preds[predIndex] = i;
        }
      }
  
  