fix(scenario): NPE when no angular loaded in test page

Author: Jimmy Zhuo

src/ngScenario/Scenario.js

@@ -294,10 +294,11 @@ function browserTrigger(element, type, keys) {
         iframe = _jQuery('#application iframe')[0],
         appWindow = iframe ? iframe.contentWindow : window,
         fakeProcessDefault = true,
-        finalProcessDefault;
+        finalProcessDefault,
+        angular = appWindow.angular || {};
 
     // igor: temporary fix for https://bugzilla.mozilla.org/show_bug.cgi?id=684208
-    appWindow.angular['ff-684208-preventDefault'] = false;
+    angular['ff-684208-preventDefault'] = false;
     evnt.preventDefault = function() {
       fakeProcessDefault = false;
       return originalPreventDefault.apply(evnt, arguments);
@@ -307,9 +308,9 @@ function browserTrigger(element, type, keys) {
                         pressed('shift'), pressed('meta'), 0, element);
 
     element.dispatchEvent(evnt);
-    finalProcessDefault = !(appWindow.angular['ff-684208-preventDefault'] || !fakeProcessDefault);
+    finalProcessDefault = !(angular['ff-684208-preventDefault'] || !fakeProcessDefault);
 
-    delete appWindow.angular['ff-684208-preventDefault'];
+    delete angular['ff-684208-preventDefault'];
 
     return finalProcessDefault;
   }