Fixed typo

lib/html/src/dart2js_Conversions.dart

Index: lib/html/src/dart2js_Conversions.dart
diff --git a/lib/html/src/dart2js_Conversions.dart b/lib/html/src/dart2js_Conversions.dart
index 8f13a42a3b8c0a90d81e9ccc3ff2d7d8836d9ca4..71aff9dd2bf83dccf3469440994ed331c69553c9 100644
--- a/lib/html/src/dart2js_Conversions.dart
+++ b/lib/html/src/dart2js_Conversions.dart
@@ -35,7 +35,7 @@ EventTarget _convertNativeToDart_EventTarget(e) {
   // from a different frame - without a patched prototype - so we cannot
   // rely on Dart type checking.
   if (JS('bool', r'"setInterval" in #', e))
-    return _DOMWindowCrossFrameImpl._createSafe(event);
+    return _DOMWindowCrossFrameImpl._createSafe(e);
   else
     return e;
 }