Add touchenter event even though it doesn't have an ontouchenter method in the DOM.

lib/html/frog/html_frog.dart

Index: lib/html/frog/html_frog.dart
diff --git a/lib/html/frog/html_frog.dart b/lib/html/frog/html_frog.dart
index 9420f5c5fb2f2d2005ea1d24023490e785f3896c..c15574faa2626350d7c853b2c22af2561b54b9df 100644
--- a/lib/html/frog/html_frog.dart
+++ b/lib/html/frog/html_frog.dart
@@ -6281,6 +6281,8 @@ class _ElementEventsImpl extends _EventsImpl implements ElementEvents {
 
   EventListenerList get touchEnd() => _get('touchend');
 
+  EventListenerList get touchEnter() => _get('touchenter');
+
   EventListenerList get touchLeave() => _get('touchleave');
 
   EventListenerList get touchMove() => _get('touchmove');
@@ -21650,6 +21652,8 @@ interface ElementEvents extends Events {
 
   EventListenerList get touchEnd();
 
+  EventListenerList get touchEnter();
+
   EventListenerList get touchLeave();
 
   EventListenerList get touchMove();