Move pub into sdk/lib/_internal.

utils/tests/pub/install/path/no_pubspec_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 d.file.
-
-import 'dart:io';
-
-import 'package:pathos/path.dart' as path;
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  integration('path dependency to non-package directory', () {
-    // Make an empty directory.
-    d.dir('foo').create();
-    var fooPath = path.join(sandboxDir, "foo");
-
-    d.dir(appPath, [
-      d.pubspec({
-        "name": "myapp",
-        "dependencies": {
-          "foo": {"path": fooPath}
-        }
-      })
-    ]).create();
-
-    schedulePub(args: ['install'],
-        error: new RegExp('Package "foo" doesn\'t have a pubspec.yaml file.'),
-        exitCode: 1);
-  });
-}