Extract testing utilities into a separate package.

pkg/analysis_server/test/analysis_notification_navigation_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library test.domain.analysis.notification.navigation;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/computer/element.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
+import 'package:analysis_testing/reflective_tests.dart';
 import 'package:unittest/unittest.dart';
 
 import 'analysis_abstract.dart';
-import 'reflective_tests.dart';
 
 
 main() {
   group('notification.navigation', () {
     runReflectiveTests(AnalysisNotificationNavigationTest);
   });
 }
 
 
 @ReflectiveTestCase()
@@ skipping 452 matching lines @@
   final int length;
   final List<Element> targets;
 
   NavigationRegion(this.offset, this.length, this.targets);
 
   @override
   String toString() {
     return 'NavigationRegion(offset=$offset; length=$length; targets=$targets';
   }
 }