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

sdk/lib/_internal/pub_generated/test/snapshot/snapshots_transformed_code_test.dart

-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS 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 'package:path/path.dart' as p;
 import 'package:scheduled_test/scheduled_test.dart';
-
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
-
 const REPLACE_TRANSFORMER = """
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 
 class ReplaceTransformer extends Transformer {
   ReplaceTransformer.asPlugin();
 
   String get allowedExtensions => '.dart';
 
   Future apply(Transform transform) {
     return transform.primaryInput.readAsString().then((contents) {
       transform.addOutput(new Asset.fromString(transform.primaryInput.id,
           contents.replaceAll("REPLACE ME", "hello!")));
     });
   }
 }
 """;
-
 main() {
   initConfig();
   integration("snapshots the transformed version of an executable", () {
     servePackages((builder) {
       builder.serveRepoPackage('barback');
-
-      builder.serve("foo", "1.2.3",
-          deps: {"barback": "any"},
-          pubspec: {'transformers': ['foo']},
+      builder.serve("foo", "1.2.3", deps: {
+        "barback": "any"
+      }, pubspec: {
+        'transformers': ['foo']
+      },
           contents: [
-        d.dir("lib", [d.file("foo.dart", REPLACE_TRANSFORMER)]),
-        d.dir("bin", [
-          d.file("hello.dart", """
+              d.dir("lib", [d.file("foo.dart", REPLACE_TRANSFORMER)]),
+              d.dir("bin", [d.file("hello.dart", """
 final message = 'REPLACE ME';
 
 void main() => print(message);
-"""),
-        ])
-      ]);
+""")])]);
     });
-
-    d.appDir({"foo": "1.2.3"}).create();
-
+    d.appDir({
+      "foo": "1.2.3"
+    }).create();
     pubGet(output: contains("Precompiled foo:hello."));
-
-    d.dir(p.join(appPath, '.pub', 'bin'), [
-      d.dir('foo', [d.matcherFile('hello.dart.snapshot', contains('hello!'))])
-    ]).validate();
-
+    d.dir(
+        p.join(appPath, '.pub', 'bin'),
+        [
+            d.dir(
+                'foo',
+                [d.matcherFile('hello.dart.snapshot', contains('hello!'))])]).validate();
     var process = pubRun(args: ['foo:hello']);
     process.stdout.expect("hello!");
     process.shouldExit();
   });
 }