Move pub into sdk/lib/_internal.

utils/tests/pub/install/git/require_pubspec_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 'dart:io';
-
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  integration('requires the dependency to have a pubspec', () {
-    ensureGit();
-
-    d.git('foo.git', [
-      d.libDir('foo')
-    ]).create();
-
-    d.appDir([{"git": "../foo.git"}]).create();
-
-    // TODO(nweiz): clean up this RegExp when either issue 4706 or 4707 is
-    // fixed.
-    schedulePub(args: ['install'],
-        error: new RegExp('^Package "foo" doesn\'t have a '
-            'pubspec.yaml file.'),
-        exitCode: 1);
-  });
-}