Start pulling pub from its own repo.

sdk/lib/_internal/pub/test/transformer/runs_a_transformer_on_a_dependency_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.
-
-library pub_tests;
-
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-import '../serve/utils.dart';
-
-main() {
-  initConfig();
-  withBarbackVersions("any", () {
-    integration("runs a local transformer on a dependency", () {
-      d.dir("foo", [
-        d.pubspec({
-          "name": "foo",
-          "version": "0.0.1",
-          "transformers": ["foo/transformer"]
-        }),
-        d.dir("lib", [
-          d.file("transformer.dart", REWRITE_TRANSFORMER),
-          d.file("foo.txt", "foo")
-        ])
-      ]).create();
-
-      d.dir(appPath, [
-        d.appPubspec({"foo": {"path": "../foo"}}),
-      ]).create();
-
-      createLockFile('myapp', sandbox: ['foo'], pkg: ['barback']);
-
-      pubServe();
-      requestShouldSucceed("packages/foo/foo.out", "foo.out");
-      endPubServe();
-    });
-  });
-}