introduce web_components pkg for consolidated polyfills

pkg/template_binding/test/custom_element_bindings_test.dart

Index: pkg/template_binding/test/custom_element_bindings_test.dart
diff --git a/pkg/template_binding/test/custom_element_bindings_test.dart b/pkg/template_binding/test/custom_element_bindings_test.dart
index d3c22c969850226b43064e9f9993206eb3e583af..62fb8ee24e12b6a33f514301973d54c73cffb19b 100644
--- a/pkg/template_binding/test/custom_element_bindings_test.dart
+++ b/pkg/template_binding/test/custom_element_bindings_test.dart
@@ -6,11 +6,11 @@ library template_binding.test.custom_element_bindings_test;
 
 import 'dart:async';
 import 'dart:html';
-import 'package:custom_element/polyfill.dart';
 import 'package:template_binding/template_binding.dart';
 import 'package:observe/observe.dart';
 import 'package:unittest/html_config.dart';
 import 'package:unittest/unittest.dart';
+import 'package:web_components/polyfill.dart';
 import 'utils.dart';
 
 Future _registered;
@@ -18,7 +18,7 @@ Future _registered;
 main() => dirtyCheckZone().run(() {
   useHtmlConfiguration();
 
-  _registered = loadCustomElementPolyfill().then((_) {
+  _registered = customElementsReady.then((_) {
     document.register('my-custom-element', MyCustomElement);
     document.register('with-attrs-custom-element', WithAttrsCustomElement);
   });