Revert "Dart2js support for custom element lifecycle events"

tests/html/custom/document_register_basic_test.dart

Index: tests/html/custom/document_register_basic_test.dart
diff --git a/tests/html/custom/document_register_basic_test.dart b/tests/html/custom/document_register_basic_test.dart
index c8964e5127c10e276cef280460fe580113c8d00f..6934a473b9bb07937627ee397ec3f103d5cddfaa 100644
--- a/tests/html/custom/document_register_basic_test.dart
+++ b/tests/html/custom/document_register_basic_test.dart
@@ -37,6 +37,18 @@ class BadE implements HtmlElement {
   factory BadE() => new Element.tag(tag);
 }
 
+loadPolyfills() {
+  if (!document.supportsRegister) {
+    // Cache blocker is a workaround for:
+    // https://code.google.com/p/dart/issues/detail?id=11834
+    var cacheBlocker = new DateTime.now().millisecondsSinceEpoch;
+    return HttpRequest.getString('/root_dart/pkg/custom_element/lib/'
+      'custom-elements.debug.js?cacheBlock=$cacheBlocker').then((code) {
+      document.head.children.add(new ScriptElement()..text = code);
+    });
+  }
+}
+
 main() {
   useHtmlConfiguration();