Get binstubs working on Windows.

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

 import 'package:scheduled_test/scheduled_stream.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 overwrite an existing binstub", () {
     d.dir("foo", [d.pubspec({
         "name": "foo",
         "executables": {
           "foo": "foo",
           "collide1": "foo",
           "collide2": "foo"
         }
@@ skipping 15 matching lines @@
     pub.stderr.expect("Executable collide2 was already installed from foo.");
     pub.stderr.expect(
         "Deactivate the other package(s) or activate bar using " "--overwrite.");
     pub.shouldExit();
     d.dir(
         cachePath,
         [
             d.dir(
                 "bin",
                 [
-                    d.matcherFile("foo", contains("foo:foo")),
-                    d.matcherFile("bar", contains("bar:bar")),
-                    d.matcherFile("collide1", contains("foo:foo")),
-                    d.matcherFile("collide2", contains("foo:foo"))])]).validate();
+                    d.matcherFile(binStubName("foo"), contains("foo:foo")),
+                    d.matcherFile(binStubName("bar"), contains("bar:bar")),
+                    d.matcherFile(binStubName("collide1"), contains("foo:foo")),
+                    d.matcherFile(binStubName("collide2"), contains("foo:foo"))])]).validate();
   });
 }