Revert "Use native async/await support in pub."

sdk/lib/_internal/pub_generated/test/dart2js/omits_source_map_in_release_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 '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   initConfig();
   integration("omits source maps from a release build", () {
-    d.dir(appPath, [
-      d.appPubspec(),
-      d.dir("web", [
-        d.file("main.dart", "void main() => print('hello');")
-      ])
-    ]).create();
+    d.dir(
+        appPath,
+        [
+            d.appPubspec(),
+            d.dir(
+                "web",
+                [d.file("main.dart", "void main() => print('hello');")])]).create();
 
-    schedulePub(args: ["build"],
+    schedulePub(
+        args: ["build"],
         output: new RegExp(r'Built 1 file to "build".'),
         exitCode: 0);
 
-    d.dir(appPath, [
-      d.dir('build', [
-        d.dir('web', [
-          d.nothing('main.dart.js.map')
-        ])
-      ])
-    ]).validate();
+    d.dir(
+        appPath,
+        [d.dir('build', [d.dir('web', [d.nothing('main.dart.js.map')])])]).validate();
   });
 }