Start pulling pub from its own repo.

sdk/lib/_internal/pub/test/run/runs_a_generated_script_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 '../descriptor.dart' as d;
-import '../test_pub.dart';
-
-const TRANSFORMER = """
-import 'dart:async';
-
-import 'package:barback/barback.dart';
-
-class DartTransformer extends Transformer {
-  DartTransformer.asPlugin();
-
-  String get allowedExtensions => '.in';
-
-  void apply(Transform transform) {
-    transform.addOutput(new Asset.fromString(
-        new AssetId("myapp", "bin/script.dart"),
-        "void main() => print('generated');"));
-  }
-}
-""";
-
-main() {
-  initConfig();
-  withBarbackVersions("any", () {
-    integration('runs a script generated from scratch by a transformer', () {
-      d.dir(appPath, [
-        d.pubspec({
-          "name": "myapp",
-          "transformers": ["myapp/src/transformer"]
-        }),
-        d.dir("lib", [d.dir("src", [
-          d.file("transformer.dart", TRANSFORMER),
-          d.file("primary.in", "")
-        ])])
-      ]).create();
-
-      createLockFile('myapp', pkg: ['barback']);
-
-      var pub = pubRun(args: ["bin/script"]);
-
-      pub.stdout.expect("generated");
-      pub.shouldExit();
-    });
-  });
-}