Get binstubs working on Windows.

sdk/lib/_internal/pub_generated/test/global/binstubs/reactivate_removes_old_executables_test.dart

 import 'package:scheduled_test/scheduled_test.dart';
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
+import 'utils.dart';
 main() {
   initConfig();
   integration("removes previous binstubs when reactivating a package", () {
     d.dir("foo", [d.pubspec({
         "name": "foo",
         "executables": {
           "one": null,
           "two": null
         }
       }),
           d.dir(
               "bin",
               [
                   d.file("one.dart", "main() => print('ok');"),
                   d.file("two.dart", "main() => print('ok');")])]).create();
     schedulePub(args: ["global", "activate", "--source", "path", "../foo"]);
     d.dir("foo", [d.pubspec({
         "name": "foo",
         "executables": {
           "two": null
         }
       })]).create();
     schedulePub(args: ["global", "activate", "--source", "path", "../foo"]);
     d.dir(
         cachePath,
         [
             d.dir(
                 "bin",
-                [d.nothing("one"), d.matcherFile("two", contains("two"))])]).validate();
+                [
+                    d.nothing(binStubName("one")),
+                    d.matcherFile(binStubName("two"), contains("two"))])]).validate();
   });
 }