Generate constants in server as we do in plugin

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.
 
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
+import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
-import 'package:analysis_server/src/constants.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../analysis_abstract.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationNavigationTest);
   });
@@ skipping 161 matching lines @@
 class AnalysisNotificationNavigationTest extends AbstractNavigationTest {
   Completer _resultsAvailable = new Completer();
 
   Future prepareNavigation() async {
     addAnalysisSubscription(AnalysisService.NAVIGATION, testFile);
     await _resultsAvailable.future;
     assertRegionsSorted();
   }
 
   void processNotification(Notification notification) {
-    if (notification.event == ANALYSIS_NAVIGATION) {
+    if (notification.event == ANALYSIS_NOTIFICATION_NAVIGATION) {
       var params = new AnalysisNavigationParams.fromNotification(notification);
       if (params.file == testFile) {
         regions = params.regions;
         targets = params.targets;
         targetFiles = params.files;
         _resultsAvailable.complete(null);
       }
     }
   }
 
@@ skipping 824 matching lines @@
   }
 
   test_var_topLevelVariable_single_notInferred() async {
     addTestFile('''
 var x;
 ''');
     await prepareNavigation();
     assertNoRegionAt('var');
   }
 }