Make server use the common protocol classes

pkg/analysis_server/test/analysis/notification_highlights_test2.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.analysis.notification.highlights2;
-
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.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(AnalysisNotificationHighlightsTest);
     defineReflectiveTests(HighlightTypeTest);
   });
@@ skipping 1083 matching lines @@
   void test_toString() {
     expect(HighlightRegionType.CLASS.toString(), 'HighlightRegionType.CLASS');
   }
 
   void test_valueOf_unknown() {
     expect(() {
       new HighlightRegionType('no-such-type');
     }, throws);
   }
 }