Get binstubs working on Windows.

sdk/lib/_internal/pub/test/global/binstubs/binstub_runs_global_run_if_no_snapshot_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 'package:scheduled_test/scheduled_test.dart';
 
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
+import 'utils.dart';
 
 main() {
   initConfig();
   integration("the binstubs runs pub global run if there is no snapshot", () {
     d.dir("foo", [
       d.pubspec({
         "name": "foo",
         "executables": {
           "foo-script": "script"
         }
       }),
       d.dir("bin", [
         d.file("script.dart", "main() => print('ok');")
       ])
     ]).create();
 
     // Path packages are mutable, so no snapshot is created.
     schedulePub(args: ["global", "activate", "--source", "path", "../foo"],
         output: contains("Installed executable foo-script."));
 
     d.dir(cachePath, [
       d.dir("bin", [
-        d.matcherFile("foo-script", contains("pub global run foo:script"))
+        d.matcherFile(binStubName("foo-script"),
+            contains("pub global run foo:script"))
       ])
     ]).validate();
   });
 }