remove extraneous classes and cleanup code

pkg/analysis_server/test/domain_completion_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.
 
 library test.domain.completion;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/channel/channel.dart';
-import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/context_manager.dart';
 import 'package:analysis_server/src/domain_analysis.dart';
 import 'package:analysis_server/src/domain_completion.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
 import 'package:analysis_server/src/provisional/completion/completion_core.dart'
     show AnalysisRequest, CompletionRequest, CompletionResult;
 import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
 import 'package:analysis_server/src/services/completion/completion_manager.dart';
 import 'package:analysis_server/src/services/completion/dart/completion_manager.dart';
 import 'package:analysis_server/src/services/completion/dart/contribution_sorter.dart';
@@ skipping 863 matching lines @@
 }
     ''');
     await waitForTasksFinished();
     Request request =
         new CompletionGetSuggestionsParams(testFile, 0).toRequest('0');
     Response response = handler.handleRequest(request);
     expect(response.error, isNotNull);
     expect(response.error.code, RequestErrorCode.NO_INDEX_GENERATED);
   }
 }