Remove unused imports in pub.

sdk/lib/_internal/pub/test/validator/directory_test.dart

 // Copyright (c) 2013, 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:path/path.dart' as path;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../../lib/src/entrypoint.dart';
 import '../../lib/src/validator.dart';
 import '../../lib/src/validator/directory.dart';
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
 Validator directory(Entrypoint entrypoint) =>
@@ skipping 24 matching lines @@
     ];
 
     for (var name in names) {
       integration('"$name"', () {
         d.dir(appPath, [d.dir(name)]).create();
         expectValidationWarning(directory);
       });
     }
   });
 }