Rename "pathos" package to "path".

pkg/pathos/test/pathos_dart2js_test.dart

-// Copyright (c) 2013, 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:unittest/unittest.dart';
-import 'package:pathos/path.dart' as path;
-
-// In the future, the default root will be window.location.href, but right now
-// that's not possible.
-
-main() {
-  group('new Builder()', () {
-    test('uses the current working directory if root is omitted', () {
-      var builder = new path.Builder();
-      expect(builder.root, '.');
-    });
-
-    test('uses URL if style is omitted', () {
-      var builder = new path.Builder();
-      expect(builder.style, path.Style.url);
-    });
-  });
-
-  test('current', () {
-    expect(path.current, '.');
-  });
-}