Made tests pass for 'jqueryui'.

jquery/jquery.d.ts

@@ -185,6 +185,10 @@ interface JQueryXHR extends XMLHttpRequest, JQueryPromise<any> {
      * Property containing the parsed response if the response Content-Type is json
      */
     responseJSON?: any;
+    /**
+     * A function to be called if the request fails.
+     */
+    error(xhr: JQueryXHR, textStatus: string, errorThrown: string): void;
 }
 
 /**