Error in extractEvents

If the event is on the window object, topScroll, for instance, the topLevelTarget will not have getAttribute defined. Restore the previous `|| !topLevelTarget.attributes` check to avoid an error on every scroll.

src/browser/eventPlugins/AnalyticsEventPluginFactory.js

@@ -149,7 +149,7 @@ function extractEvents(
     topLevelTargetID,
     nativeEvent) {
   var currentEvent = topLevelTypesToAnalyticsEvent[topLevelType];
-  if (!currentEvent || !topLevelTarget) {
+  if (!currentEvent || !topLevelTarget || !topLevelTarget.attributes) {
     return null;
   }