anchor.diff:    final String _msg;
     const _InternalMirrorError(String this._msg);
     String toString() => _msg;
  -}
  -
  -Map _filterMap(Map<Symbol, dynamic> old_map, bool filter(Symbol key, value)) {
  -  Map new_map = new Map<Symbol, dynamic>();
  -  old_map.forEach((key, value) {
  -    if (filter(key, value)) {
  -      new_map[key] = value;
  -    }
  -  });
  -  return new UnmodifiableMapView(new_map);
   }
   
   Map _makeMemberMap(List mirrors) {
  
positive.code:   get typeVariables => emptyList;
    get typeArguments => emptyList;
    get metadata => emptyList;
    Map<Symbol, Mirror> get members => emptyMap;
    Map<Symbol, MethodMirror> get constructors => emptyMap;
  
    String toString() => "FunctionTypeMirror on '${_n(simpleName)}'";
  
  
negative.code:     return _cachedMembers;
    }
  
    Map<Symbol, MethodMirror> _cachedConstructors;
    Map<Symbol, MethodMirror> get _constructors {
      if (_cachedConstructors == null) {
  