fix findController for non-dart elements

pkg/polymer/lib/src/events.dart

Index: pkg/polymer/lib/src/events.dart
diff --git a/pkg/polymer/lib/src/events.dart b/pkg/polymer/lib/src/events.dart
index 881728a65c80619c0f5b6ff4d7480956229d3b5a..3fc71ad0e759ce32ab5f5a3ee926b66450186863 100644
--- a/pkg/polymer/lib/src/events.dart
+++ b/pkg/polymer/lib/src/events.dart
@@ -52,6 +52,12 @@ abstract class PolymerEventBindings {
     while (node.parentNode != null) {
       if (node is Polymer && node.eventController != null) {
         return node.eventController;
+      } else if (node is Element) {
+        // If it is a normal element, js polymer element, or dart wrapper to a
+        // js polymer element, then we try js interop.
+        var eventController =
+            new JsObject.fromBrowserObject(node)['eventController'];
+        if (eventController != null) return eventController;
       }
       node = node.parentNode;
     }