Make server use the common protocol classes

pkg/analysis_server/test/integration/analysis/analysis_options_test.dart

 // Copyright (c) 2015, 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/src/generated/engine.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(OptionsIntegrationTest);
   });
 }
@@ skipping 59 matching lines @@
     AnalysisError error = errors[0];
     expect(error.location.file, options);
     expect(error.severity, AnalysisErrorSeverity.WARNING);
     expect(error.type, AnalysisErrorType.STATIC_WARNING);
     expect(error.location.offset, 23);
     expect(error.location.length, 'camel_case_typo'.length);
     expect(error.location.startLine, 3);
     expect(error.location.startColumn, 7);
   }
 }