anchor.diff:            return true;
           }
         }
  -      i = _HashBase._nextProbe(i, probeDistance, sizeMask);
  -      probeDistance += 1;
  +      i = _HashBase._nextProbe(i, sizeMask);
         pair = _index[i];
       }
       return false;
  
positive.code:     int i = _HashBase._firstProbe(fullHash, sizeMask);
      int firstDeleted = -1;
      int pair = index[i];
      int probeDistance = 1;
      while (pair != _HashBase._UNUSED_PAIR) {
        if (pair == _HashBase._DELETED_PAIR) {
          if (firstDeleted < 0) {
  
negative.code:   }
  
    void _createIndex() {
      final size = _roundUpToPowerOfTwo(
          max(_data.length * 2, _HashBase._INITIAL_INDEX_SIZE));
      final index = new Uint32List(size);
  