Use pub list-package-dirs in analyzer command line

pkg/analysis_server/test/context_manager_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.context.directory.manager;
 
 import 'package:analysis_server/src/context_manager.dart';
-import 'package:analysis_server/src/package_map_provider.dart';
 import 'reflective_tests.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
+import 'package:analyzer/source/package_map_provider.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:path/path.dart';
 import 'package:unittest/unittest.dart';
 
 import 'mocks.dart';
 
 
 main() {
   groupSep = ' | ';
@@ skipping 675 matching lines @@
     currentContextFilePaths.remove(path);
     currentContextPackageMaps.remove(path);
   }
 
   @override
   void updateContextPackageMap(Folder contextFolder, Map<String,
       List<Folder>> packageMap) {
     currentContextPackageMaps[contextFolder.path] = packageMap;
   }
 }