anchor.diff:  
   /// A routing table for [PointerEvent] events.
   class PointerRouter {
  -  final Map<int, LinkedHashSet<_RouteEntry>> _routeMap = <int, LinkedHashSet<_RouteEntry>>{};
  -  final LinkedHashSet<_RouteEntry> _globalRoutes = LinkedHashSet<_RouteEntry>();
  +  final Map<int, Map<PointerRoute, Matrix4>> _routeMap = <int, Map<PointerRoute, Matrix4>>{};
  +  final Map<PointerRoute, Matrix4> _globalRoutes = <PointerRoute, Matrix4>{};
   
     /// Adds a route to the routing table.
     ///
  
positive.code:   /// Routes added reentrantly within [PointerRouter.route] will take effect when
    /// routing the next event.
    void addGlobalRoute(PointerRoute route, [Matrix4 transform]) {
      assert(!_globalRoutes.any(_RouteEntry.isRoutePredicate(route)));
      _globalRoutes.add(_RouteEntry(route: route, transform: transform));
    }
  
    /// Removes a route from the global entry in the routing table.
  
negative.code:   /// The pointer event that was being routed when the exception was raised.
    final PointerEvent event;
  }
  