MT#5435 Fixed missed button 'Create Special Off-Peak Date'

We cannot use length here because helper.top_buttons is not a scalar

Change-Id: I35085713161e85628ffc1bb528efe7fd7b4a3d7f

share/templates/helpers/datatables.tt

@@ -184,7 +184,7 @@ $(document).ready(function() {
 } );
 </script>
 
-[% IF (!back_created) || helper.top_buttons.length -%]
+[% IF (!back_created) || helper.top_buttons.size -%]
     <div class="row">
         [% UNLESS back_created -%]
         <span class="pull-left" style="margin:0 5px 0 5px;">