Generate constants in server as we do in plugin

pkg/analysis_server/test/analysis/notification_overrides_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:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../analysis_abstract.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationOverridesTest);
   });
 }
@@ skipping 96 matching lines @@
           '${overridesList.join('\n')}');
     }
   }
 
   Future prepareOverrides() {
     addAnalysisSubscription(AnalysisService.OVERRIDES, testFile);
     return _resultsAvailable.future;
   }
 
   void processNotification(Notification notification) {
-    if (notification.event == ANALYSIS_OVERRIDES) {
+    if (notification.event == ANALYSIS_NOTIFICATION_OVERRIDES) {
       var params = new AnalysisOverridesParams.fromNotification(notification);
       if (params.file == testFile) {
         overridesList = params.overrides;
         _resultsAvailable.complete(null);
       }
     }
   }
 
   void setUp() {
     super.setUp();
@@ skipping 433 matching lines @@
 class B extends A {
   set fff(x) {} // in B
 }
 ''');
     await prepareOverrides();
     assertHasOverride('fff(x) {} // in B');
     assertHasSuperElement('fff(x) {} // in A');
     assertNoInterfaceMembers();
   }
 }