Move PathObserver to mdv_observe package

pkg/mdv_observe/test/path_observer_test.dart

Index: pkg/mdv_observe/test/path_observer_test.dart
diff --git a/tests/html/path_observer_test.dart b/pkg/mdv_observe/test/path_observer_test.dart
similarity index 98%
rename from tests/html/path_observer_test.dart
rename to pkg/mdv_observe/test/path_observer_test.dart
index d6db89b1c5bd37504a2f9e0fa9b78450b79c295b..ef62025d51fa43b7b8850322ed448b990a1e007d 100644
--- a/tests/html/path_observer_test.dart
+++ b/pkg/mdv_observe/test/path_observer_test.dart
@@ -2,8 +2,6 @@
 // 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 'dart:html' show PathObserver;
-import 'package:unittest/html_config.dart';
 import 'package:mdv_observe/mdv_observe.dart';
 import 'package:unittest/unittest.dart';
 
@@ -11,7 +9,6 @@ import 'package:unittest/unittest.dart';
 // https://github.com/rafaelw/ChangeSummary/blob/master/tests/test.js
 
 main() {
-  useHtmlConfiguration();
   group('PathObserver', observePathTests);
 }