Generate constants in server as we do in plugin

pkg/analysis_server/test/analysis_abstract.dart

Index: pkg/analysis_server/test/analysis_abstract.dart
diff --git a/pkg/analysis_server/test/analysis_abstract.dart b/pkg/analysis_server/test/analysis_abstract.dart
index 8d0348ecd5ddb7a0b63edfec376af5abe5836da3..573c607c9e10c29c2f56e69287ba309a5ce3f451 100644
--- a/pkg/analysis_server/test/analysis_abstract.dart
+++ b/pkg/analysis_server/test/analysis_abstract.dart
@@ -5,10 +5,10 @@
 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'
     hide AnalysisOptions;
 import 'package:analysis_server/src/analysis_server.dart';
-import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/domain_analysis.dart';
 import 'package:analysis_server/src/plugin/notification_manager.dart';
 import 'package:analysis_server/src/plugin/plugin_manager.dart';
@@ -205,7 +205,7 @@ class AbstractAnalysisTest {
   }
 
   void processNotification(Notification notification) {
-    if (notification.event == SERVER_ERROR) {
+    if (notification.event == SERVER_NOTIFICATION_ERROR) {
       var params = new ServerErrorParams.fromNotification(notification);
       serverErrors.add(params);
     }