Reuse _dispatchEvent for sync message sending.

lib/dom/templates/html/dartium/html_dartium.darttemplate

Index: lib/dom/templates/html/dartium/html_dartium.darttemplate
diff --git a/lib/dom/templates/html/dartium/html_dartium.darttemplate b/lib/dom/templates/html/dartium/html_dartium.darttemplate
index f9e4f45bc5f68f33fcb9e1b09968f4c729b9a35f..f7b9120b14a5686fa67da7989c50f260391276f3 100644
--- a/lib/dom/templates/html/dartium/html_dartium.darttemplate
+++ b/lib/dom/templates/html/dartium/html_dartium.darttemplate
@@ -82,11 +82,8 @@ _callPortSync(num id, var message) {
     }, false);
     _callPortInitialized = true;
   }
-  var data = JSON.stringify({ 'id': id, 'message': message });
-  var event = document.$dom_createEvent('TextEvent');
-  event.initTextEvent('js-sync-message', false, false, window, data);
   assert(_callPortLastResult == null);
-  window.$dom_dispatchEvent(event);
+  _dispatchEvent('js-sync-message', {'id': id, 'message': message});
   var result = _callPortLastResult;
   _callPortLastResult = null;
   return result;