Add a --[no]-packages-dir flag.

test/no_packages_dir_test.dart

 // Copyright (c) 2014, 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 'package:scheduled_test/scheduled_test.dart';
 
 import 'descriptor.dart' as d;
 import 'test_pub.dart';
 
 main() {
   forBothPubGetAndUpgrade((command) {
-    group("with --no-package-symlinks", () {
+    group("with --no-packages-dir", () {
       integration("installs hosted dependencies to the cache", () {
         servePackages((builder) {
           builder.serve("foo", "1.0.0");
           builder.serve("bar", "1.0.0");
         });
 
         d.appDir({"foo": "any", "bar": "any"}).create();
 
-        pubCommand(command, args: ["--no-package-symlinks"]);
+        pubCommand(command, args: ["--no-packages-dir"]);
 
         d.nothing("$appPath/packages").validate();
 
         d.hostedCache([
           d.dir("foo-1.0.0", [
             d.dir("lib", [d.file("foo.dart", 'main() => "foo 1.0.0";')])
           ]),
           d.dir("bar-1.0.0", [
             d.dir("lib", [d.file("bar.dart", 'main() => "bar 1.0.0";')])
           ])
         ]).validate();
       });
 
       integration("installs git dependencies to the cache", () {
         ensureGit();
 
         d.git('foo.git', [
           d.libDir('foo'),
           d.libPubspec('foo', '1.0.0')
         ]).create();
 
         d.appDir({"foo": {"git": "../foo.git"}}).create();
 
-        pubCommand(command, args: ["--no-package-symlinks"]);
+        pubCommand(command, args: ["--no-packages-dir"]);
 
         d.nothing("$appPath/packages").validate();
 
         d.dir(cachePath, [
           d.dir('git', [
             d.dir('cache', [d.gitPackageRepoCacheDir('foo')]),
             d.gitPackageRevisionCacheDir('foo')
           ])
         ]).validate();
       });
 
       integration("locks path dependencies", () {
         d.dir("foo", [
           d.libDir("foo"),
           d.libPubspec("foo", "0.0.1")
         ]).create();
 
         d.dir(appPath, [
           d.appPubspec({
             "foo": {"path": "../foo"}
           })
         ]).create();
 
-        pubCommand(command, args: ["--no-package-symlinks"]);
+        pubCommand(command, args: ["--no-packages-dir"]);
 
         d.nothing("$appPath/packages").validate();
         d.matcherFile("$appPath/pubspec.lock", contains("foo"));
       });
 
       integration("removes package directories near entrypoints", () {
         d.dir(appPath, [
           d.appPubspec(),
           d.dir("packages"),
           d.dir("bin/packages"),
           d.dir("web/packages"),
           d.dir("web/subdir/packages")
         ]).create();
 
-        pubCommand(command, args: ["--no-package-symlinks"]);
+        pubCommand(command, args: ["--no-packages-dir"]);
 
         d.dir(appPath, [
           d.nothing("packages"),
           d.nothing("bin/packages"),
           d.nothing("web/packages"),
           d.nothing("web/subdir/packages")
         ]).validate();
       });
 
       integration("doesn't remove package directories that pub wouldn't "
           "generate", () {
         d.dir(appPath, [
           d.appPubspec(),
           d.dir("packages"),
           d.dir("bin/subdir/packages"),
           d.dir("lib/packages")
         ]).create();
 
-        pubCommand(command, args: ["--no-package-symlinks"]);
+        pubCommand(command, args: ["--no-packages-dir"]);
 
         d.dir(appPath, [
           d.nothing("packages"),
           d.dir("bin/subdir/packages"),
           d.dir("lib/packages")
         ]).validate();
       });
     });
   });
 }