Store the async-await compiled pub code directly in the repo.

sdk/lib/_internal/pub_generated/test/dart2js/compiles_generated_dart_file_test.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.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 '../serve/utils.dart';
-
 main() {
   initConfig();
   withBarbackVersions("any", () {
     integration("compiles a generated Dart file to JS", () {
-      d.dir(appPath, [
-        d.pubspec({
+      d.dir(appPath, [d.pubspec({
           "name": "myapp",
           "version": "0.0.1",
           "transformers": ["myapp/transformer"]
         }),
-        d.dir("lib", [
-          d.file("transformer.dart", dartTransformer("munge"))
-        ]),
-        d.dir("web", [
-          d.file("main.dart", """
+            d.dir("lib", [d.file("transformer.dart", dartTransformer("munge"))]),
+            d.dir("web", [d.file("main.dart", """
 const TOKEN = "before";
 void main() => print(TOKEN);
-""")
-        ])
-      ]).create();
-
+""")])]).create();
       createLockFile('myapp', pkg: ['barback']);
-
       pubServe();
       requestShouldSucceed("main.dart.js", contains("(before, munge)"));
       endPubServe();
     });
   });
 }