Get binstubs working on Windows.

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

 import 'package:scheduled_test/scheduled_test.dart';
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
+import 'utils.dart';
 main() {
   initConfig();
   integration("does not create binstubs if --no-executables is passed", () {
     d.dir("foo", [d.pubspec({
         "name": "foo",
         "executables": {
           "one": null
         }
       }),
           d.dir("bin", [d.file("one.dart", "main() => print('ok');")])]).create();
     schedulePub(args: ["global", "activate", "--source", "path", "../foo"]);
     schedulePub(
         args: ["global", "activate", "--source", "path", "../foo", "--no-executables"]);
-    d.dir(cachePath, [d.dir("bin", [d.nothing("one")])]).validate();
+    d.dir(
+        cachePath,
+        [d.dir("bin", [d.nothing(binStubName("one"))])]).validate();
   });
 }