anchor.diff:    }
   }
   
  -abstract class LocalHistoryRoute<T> extends TransitionRoute<T> {
  -  LocalHistoryRoute({
  -    Completer<T> popCompleter,
  -    Completer<T> transitionCompleter
  -  }) : super(
  -    popCompleter: popCompleter,
  -    transitionCompleter: transitionCompleter
  -  );
  -
  +abstract class LocalHistoryRoute<T> extends Route<T> {
     List<LocalHistoryEntry> _localHistory;
     void addLocalHistoryEntry(LocalHistoryEntry entry) {
       assert(entry._owner == null);
  
positive.code:     Completer<T> transitionCompleter
    }) : _popCompleter = popCompleter,
         _transitionCompleter = transitionCompleter;
  
    /// This future completes once the animation has been dismissed. For
    /// ModalRoutes, this will be after the completer that's passed in, since that
  
negative.code:   final double left;
  }
  
  abstract class ModalRoute<T> extends TransitionRoute<T> with LocalHistoryRoute<T> {
    ModalRoute({
      Completer<T> completer,
      this.settings: const NamedRouteSettings()
    }) : super.explicit(completer, null);
  
    // The API for general users of this class
  
  