Revert "Dart2js support for custom element lifecycle events"

tests/html/custom/document_register_type_extensions_test.dart

Index: tests/html/custom/document_register_type_extensions_test.dart
diff --git a/tests/html/custom/document_register_type_extensions_test.dart b/tests/html/custom/document_register_type_extensions_test.dart
index 79b036df6c1caef674cad0ef24ec5799ce7db8f6..cf1337493fc39fceb813a6fe7c1da77167ed59da 100644
--- a/tests/html/custom/document_register_type_extensions_test.dart
+++ b/tests/html/custom/document_register_type_extensions_test.dart
@@ -40,6 +40,18 @@ class FooBad extends DivElement {
   factory FooBad() => new Element.tag('div', 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() {
   useHtmlIndividualConfiguration();