Fix filters for In App Notifications

src/extensions/default/InAppNotifications/main.js

@@ -213,17 +213,28 @@ define(function (require, exports, module) {
     }
 
     function _checkExtensions(filters) {
+        //if no property called extensions then it's a universal notification
+        if (filters.extensions === undefined) {
+            return true;
+        }
+
         var allExtensions = ExtensionManager.extensions,
             allExtnsMatched = true,
             userExtensionKeys = Object.keys(allExtensions).filter(function(k) {
                 return allExtensions[k].installInfo.locationType === 'user';
             });
 
         if (!filters.extensions) {
-            allExtnsMatched = userExtensionKeys.size === 0;
+            //if property called extensions exists but has a falsy value
+            //then number of user extensions must be zero
+            allExtnsMatched = userExtensionKeys.length === 0;
         } else if (filters.extensions.length === 0) {
+            //if property called extensions exists but is an empty array
+            //then number of user extensions must greater than zero
             allExtnsMatched = userExtensionKeys.length > 0;
         } else {
+            //if property called extensions exists but is a non empty array
+            //then notification is targetted to users having the fitered extensions
             var filteredExtns = filters.extensions,
                 extnIterator = null;
             for (var i=0; i < filteredExtns.length; i++) {