Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/global/activate/activate_path_after_hosted_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.
-
-import 'package:path/path.dart' as p;
-
-import '../../../lib/src/io.dart';
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  integration('activating a hosted package deactivates the path one', () {
-    servePackages((builder) {
-      builder.serve(
-          "foo",
-          "1.0.0",
-          contents: [
-              d.dir("bin", [d.file("foo.dart", "main(args) => print('hosted');")])]);
-    });
-
-    d.dir(
-        "foo",
-        [
-            d.libPubspec("foo", "2.0.0"),
-            d.dir("bin", [d.file("foo.dart", "main() => print('path');")])]).create();
-
-    schedulePub(args: ["global", "activate", "foo"]);
-
-    var path = canonicalize(p.join(sandboxDir, "foo"));
-    schedulePub(args: ["global", "activate", "-spath", "../foo"], output: """
-        Package foo is currently active at version 1.0.0.
-        Activated foo 2.0.0 at path "$path".""");
-
-    // Should now run the path one.
-    var pub = pubRun(global: true, args: ["foo"]);
-    pub.stdout.expect("path");
-    pub.shouldExit();
-  });
-}