Get binstubs working on Windows.

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

 import 'package:scheduled_test/scheduled_test.dart';
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
+import 'utils.dart';
 main() {
   initConfig();
   integration("creates binstubs for each executable in the pubspec", () {
     servePackages((builder) {
       builder.serve("foo", "1.0.0", pubspec: {
         "executables": {
           "one": null,
           "two-renamed": "second"
         }
       },
           contents: [
               d.dir(
                   "bin",
                   [
                       d.file("one.dart", "main(args) => print('one');"),
                       d.file("second.dart", "main(args) => print('two');"),
                       d.file("nope.dart", "main(args) => print('nope');")])]);
     });
     schedulePub(
         args: ["global", "activate", "foo"],
         output: contains("Installed executables one and two-renamed."));
     d.dir(
         cachePath,
         [
             d.dir(
                 "bin",
                 [
-                    d.matcherFile("one", contains("one")),
-                    d.matcherFile("two-renamed", contains("second")),
-                    d.nothing("two"),
-                    d.nothing("nope")])]).validate();
+                    d.matcherFile(binStubName("one"), contains("one")),
+                    d.matcherFile(binStubName("two-renamed"), contains("second")),
+                    d.nothing(binStubName("two")),
+                    d.nothing(binStubName("nope"))])]).validate();
   });
 }