anchor.diff:  }
   
   class _CompactIterator<E> implements Iterator<E> {
  -  final _table;
  +  final _HashBase _table;
     final List _data;
     final int _len;
     int _offset;
  
positive.code:   }
  }
  
  abstract class _LinkedHashMapMixin<K, V> implements _HashVMBase {
    int _hashCode(e);
    bool _equals(e1, e2);
    int get _checkSum;
  
negative.code: // Iterates through _data[_offset + _step], _data[_offset + 2*_step], ...
  // and checks for concurrent modification.
  class _CompactIterable<E> extends Iterable<E> {
    final _HashBase _table;
    final List _data;
    final int _len;
    final int _offset;
  