Fixed leak and removed no-shuffle tag in test/widgets/routes_test.dart (#88881)

packages/flutter/test/widgets/routes_test.dart

@@ -2,12 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// TODO(gspencergoog): Remove this tag once this test's state leaks/test
-// dependencies have been fixed.
-// https://github.com/flutter/flutter/issues/85160
-// Fails with "flutter test --test-randomize-ordering-seed=123"
-@Tags(<String>['no-shuffle'])
-
 import 'dart:collection';
 
 import 'package:flutter/material.dart';
@@ -461,6 +455,9 @@ void main() {
       <String>[
       ],
     );
+    await tester.pumpWidget(Container());
+    expect(routes.isEmpty, isTrue);
+    results.clear();
   });
 
   group('PageRouteObserver', () {