Make server use the common protocol classes

pkg/analysis_server/test/integration/analysis/update_content_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 'package:analysis_server/protocol/protocol_generated.dart';
+import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../support/integration_tests.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UpdateContentTest);
   });
 }
@@ skipping 84 matching lines @@
 }
 ''')
     });
     await analysisFinished;
     expect(currentAnalysisErrors[pathname], isList);
     List<AnalysisError> errors2 = currentAnalysisErrors[pathname];
     expect(errors2, hasLength(1));
     expect(errors2[0].location.file, equals(pathname));
   }
 }