Update unittest to new package layout.

utils/tests/pub/pub_update_git_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('test_pub.dart');
-#import('../../../pkg/unittest/unittest.dart');
+#import('../../../pkg/unittest/lib/unittest.dart');
 
 main() {
   test("updates locked Git packages", () {
     ensureGit();
 
     git('foo.git', [
       libDir('foo')
     ]).scheduleCreate();
 
     git('bar.git', [
@@ skipping 131 matching lines @@
         ]),
         dir('foo-dep', [
           file('foo-dep.dart', 'main() => "foo-dep";')
         ]),
       ]).scheduleValidate();
 
       run();
     });
   });
 }