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

sdk/lib/_internal/pub_generated/test/cache/add/no_matching_version_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 '../../test_pub.dart';
 
 main() {
   initConfig();
   integration('fails if no version matches the version constraint', () {
     servePackages((builder) {
       builder.serve("foo", "1.2.2");
       builder.serve("foo", "1.2.3");
     });
 
-    schedulePub(args: ["cache", "add", "foo", "-v", ">2.0.0"],
+    schedulePub(
+        args: ["cache", "add", "foo", "-v", ">2.0.0"],
         error: 'Package foo has no versions that match >2.0.0.',
         exitCode: 1);
   });
 }