Check screen limit is None before comparing

issue11015
review389361002
(grafted from 28d16a85ee0d4bb2c7b160e7ee859f7badea216d)

--HG--
branch : 6.0

src/tab.js

@@ -1482,7 +1482,9 @@
                     'disabled', this.screen.readonly);
 
                 var msg = name + ' / ' + data[1];
-                if ((data[1] < data[2]) && (data[2] > this.screen.limit)) {
+                if ((data[1] < data[2]) &&
+                    this.screen.limit !== null &&
+                    (data[2] > this.screen.limit)) {
                     msg += Sao.i18n.gettext(' of ') + data[2];
                 }
                 this.status_label.text(msg).attr('title', msg);