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

test/get/hosted/stay_locked_if_new_is_satisfied_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("doesn't unlock dependencies if a new dependency is already "
       "satisfied", () {
     servePackages((builder) {
       builder.serve("foo", "1.0.0", deps: {"bar": "<2.0.0"});
       builder.serve("bar", "1.0.0", deps: {"baz": "<2.0.0"});
       builder.serve("baz", "1.0.0");
     });
 
     d.appDir({"foo": "any"}).create();
 
     pubGet();
 
-    d.packagesDir({
+    d.appPackagesFile({
       "foo": "1.0.0",
       "bar": "1.0.0",
       "baz": "1.0.0"
     }).validate();
 
     globalPackageServer.add((builder) {
       builder.serve("foo", "2.0.0", deps: {"bar": "<3.0.0"});
       builder.serve("bar", "2.0.0", deps: {"baz": "<3.0.0"});
       builder.serve("baz", "2.0.0");
       builder.serve("newdep", "2.0.0", deps: {"baz": ">=1.0.0"});
     });
 
     d.appDir({"foo": "any", "newdep": "any"}).create();
 
     pubGet();
 
-    d.packagesDir({
+    d.appPackagesFile({
       "foo": "1.0.0",
       "bar": "1.0.0",
       "baz": "1.0.0",
       "newdep": "2.0.0"
     }).validate();
   });
 }