Update pkg/path to use "package:" imports.

pkg/path/test/path_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 all_test;
 
 import 'dart:io' as io;
 
-// TODO(rnystrom): Use "package:" path when #7491 is fixed.
-import '../../unittest/lib/unittest.dart';
-import '../lib/path.dart' as path;
+import 'package:unittest/unittest.dart';
+import 'package:path/path.dart' as path;
 
 main() {
   group('path.Style', () {
     test('name', () {
       expect(path.Style.posix.name, 'posix');
       expect(path.Style.windows.name, 'windows');
     });
 
     test('separator', () {
       expect(path.Style.posix.separator, '/');
@@ skipping 29 matching lines @@
       } else {
         expect(builder.style, path.Style.posix);
       }
     });
   });
 
   test('current', () {
     expect(path.current, new io.Directory.current().path);
   });
 }