Remove unused imports in pub.

sdk/lib/_internal/pub/test/install/path/nonexistent_dir_test.dart

Index: sdk/lib/_internal/pub/test/install/path/nonexistent_dir_test.dart
diff --git a/sdk/lib/_internal/pub/test/install/path/nonexistent_dir_test.dart b/sdk/lib/_internal/pub/test/install/path/nonexistent_dir_test.dart
index f97f345e4e0029357683a612edbd71383a514b0c..3137dad878a0c3f7778d4c6a827896dfeba93d5e 100644
--- a/sdk/lib/_internal/pub/test/install/path/nonexistent_dir_test.dart
+++ b/sdk/lib/_internal/pub/test/install/path/nonexistent_dir_test.dart
@@ -2,10 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE d.file.
 
-import 'dart:io';
-
 import 'package:path/path.dart' as path;
-import 'package:scheduled_test/scheduled_test.dart';
 
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';