Fix pathos_dartium_test to use html_config

pkg/pathos/test/pathos_dartium_test.dart

Index: pkg/pathos/test/pathos_dartium_test.dart
diff --git a/pkg/pathos/test/pathos_dartium_test.dart b/pkg/pathos/test/pathos_dartium_test.dart
index 12691a5dcf2748cc502e028d36a853743255a4ba..f03abc6a6173f98f1d938c5e17279c44e0c004e3 100644
--- a/pkg/pathos/test/pathos_dartium_test.dart
+++ b/pkg/pathos/test/pathos_dartium_test.dart
@@ -5,9 +5,12 @@
 import 'dart:html';
 
 import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
 import 'package:pathos/path.dart' as path;
 
 main() {
+  useHtmlConfiguration();
+
   group('new Builder()', () {
     test('uses the current working directory if root is omitted', () {
       var builder = new path.Builder();