Make server use the common protocol classes

pkg/analysis_server/test/integration/edit/get_fixes_test.dart

 // Copyright (c) 2017, 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(GetFixesTest);
   });
 }
@@ skipping 41 matching lines @@
 Future f;
 ''';
     writeFile(pathname, text);
     standardAnalysisSetup();
 
     EditGetFixesResult result =
         await sendEditGetFixes(pathname, text.indexOf('Future f'));
     expect(result.fixes, isEmpty);
   }
 }