Simplify feed auto-detection code.

--HG--
extra : rebase_source : 70d362bc1b442c52336a34038fc2facc2f460c8c

common/content/util.js

@@ -11,6 +11,14 @@ const NS = Namespace("liberator", "http://vimperator.org/namespaces/liberator");
 default xml namespace = XHTML;
 
 const util = { //{{{
+    /**
+     * Returns true if its argument is an Array object, regardless
+     * of which context it comes from.
+     *
+     * @param {object} obj
+     */
+    isArray: function isArray(obj) Object.prototype.toString.call(obj) == "[object Array]",
+
     /**
      * Returns a shallow copy of <b>obj</b>.
      *