Call responsiveNav() if it exists Bug 1305361

This function is only available in responsive themes like 'default'

Change-Id: Ia0dc4e0c339c8d67293bcd3cf2197ad002d0a85d
Signed-off-by: Son Nguyen <son.nguyen@catalyst.net.nz>

htdocs/js/tabs.js

@@ -129,7 +129,9 @@
         );
 
         // Make the tabs responsive
-        responsiveNav($j('.tabswrap ul li'), $j('.tabswrap'));
+        if (typeof responsiveNav === 'function') {
+            responsiveNav($j('.tabswrap ul li'), $j('.tabswrap'));
+        }
 
         // Now unhide the form
         hideElement(formid + '-loading');