Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/hosted/remove_removed_transitive_dependency_test.dart

-// Copyright (c) 2012, 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 '../descriptor.dart' as d;
-import '../test_pub.dart';
-
-main() {
-  initConfig();
-
-  forBothPubGetAndUpgrade((command) {
-    integration(
-        "removes a transitive dependency that's no longer depended " "on",
-        () {
-      servePackages((builder) {
-        builder.serve("foo", "1.0.0", deps: {
-          "shared-dep": "any"
-        });
-        builder.serve("bar", "1.0.0", deps: {
-          "shared-dep": "any",
-          "bar-dep": "any"
-        });
-        builder.serve("shared-dep", "1.0.0");
-        builder.serve("bar-dep", "1.0.0");
-      });
-
-      d.appDir({
-        "foo": "any",
-        "bar": "any"
-      }).create();
-
-      pubCommand(command);
-
-      d.packagesDir({
-        "foo": "1.0.0",
-        "bar": "1.0.0",
-        "shared-dep": "1.0.0",
-        "bar-dep": "1.0.0",
-      }).validate();
-
-      d.appDir({
-        "foo": "any"
-      }).create();
-
-      pubCommand(command);
-
-      d.packagesDir({
-        "foo": "1.0.0",
-        "bar": null,
-        "shared-dep": "1.0.0",
-        "bar-dep": null,
-      }).validate();
-    });
-  });
-}