Remove uses of the old plugin model from the analysis server

pkg/analysis_server/test/edit/sort_members_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 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/edit/edit_domain.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
-import 'package:plugin/manager.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SortMembersTest);
   });
 }
 
 @reflectiveTest
 class SortMembersTest extends AbstractAnalysisTest {
   SourceFileEdit fileEdit;
 
   @override
   void setUp() {
     super.setUp();
     createProject();
-    ExtensionManager manager = new ExtensionManager();
-    manager.processPlugins([server.serverPlugin]);
     handler = new EditDomainHandler(server);
   }
 
   @failingTest
   test_BAD_doesNotExist() async {
     // The analysis driver fails to return an error
     Request request =
         new EditSortMembersParams('/no/such/file.dart').toRequest('0');
     Response response = await waitResponse(request);
     expect(response,
@@ skipping 206 matching lines @@
     expect(resultCode, expectedCode);
   }
 
   Future _requestSort() async {
     Request request = new EditSortMembersParams(testFile).toRequest('0');
     Response response = await waitResponse(request);
     var result = new EditSortMembersResult.fromResponse(response);
     fileEdit = result.edit;
   }
 }