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

sdk/lib/_internal/pub_generated/test/build/allows_arbitrary_modes_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.
-
 library pub_tests;
-
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
-
 const TRANSFORMER = """
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 
 class ModeTransformer extends Transformer {
   final BarbackSettings settings;
   ModeTransformer.asPlugin(this.settings);
 
   String get allowedExtensions => '.txt';
 
   Future apply(Transform transform) {
     return new Future.value().then((_) {
       var id = transform.primaryInput.id.changeExtension(".out");
       transform.addOutput(new Asset.fromString(id, settings.mode.toString()));
     });
   }
 }
 """;
-
 main() {
   initConfig();
   withBarbackVersions("any", () {
     integration("allows user-defined mode names", () {
-      d.dir(appPath, [
-        d.pubspec({
+      d.dir(appPath, [d.pubspec({
           "name": "myapp",
           "transformers": ["myapp/src/transformer"]
         }),
-        d.dir("lib", [d.dir("src", [
-          d.file("transformer.dart", TRANSFORMER)
-        ])]),
-        d.dir("web", [
-          d.file("foo.txt", "foo")
-        ])
-      ]).create();
-
+            d.dir("lib", [d.dir("src", [d.file("transformer.dart", TRANSFORMER)])]),
+            d.dir("web", [d.file("foo.txt", "foo")])]).create();
       createLockFile('myapp', pkg: ['barback']);
-
       schedulePub(args: ["build", "--mode", "depeche"]);
-
-      d.dir(appPath, [
-        d.dir('build', [
-          d.dir('web', [
-            d.file('foo.out', 'depeche')
-          ])
-        ])
-      ]).validate();
+      d.dir(
+          appPath,
+          [d.dir('build', [d.dir('web', [d.file('foo.out', 'depeche')])])]).validate();
     });
   });
 }