Move pub into sdk/lib/_internal.

sdk/lib/_internal/pub/test/install/hosted/install_transitive_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';
@@ skipping 10 matching lines @@
 
     d.appDir([dependencyMap("foo", "1.2.3")]).create();
 
     schedulePub(args: ['install'],
         output: new RegExp("Dependencies installed!\$"));
 
     d.cacheDir({"foo": "1.2.3", "bar": "2.0.4"}).validate();
     d.packagesDir({"foo": "1.2.3", "bar": "2.0.4"}).validate();
   });
 }