Make "--no-packages-dir" the default.

test/get/hosted/get_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.
 
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 main() {
   integration('gets packages transitively from a pub server', () {
     servePackages((builder) {
       builder.serve("foo", "1.2.3", deps: {"bar": "2.0.4"});
       builder.serve("bar", "2.0.3");
       builder.serve("bar", "2.0.4");
       builder.serve("bar", "2.0.5");
     });
 
     d.appDir({"foo": "1.2.3"}).create();
 
     pubGet();
 
     d.cacheDir({"foo": "1.2.3", "bar": "2.0.4"}).validate();
-    d.packagesDir({"foo": "1.2.3", "bar": "2.0.4"}).validate();
+    d.appPackagesFile({"foo": "1.2.3", "bar": "2.0.4"}).validate();
   });
 }