Error when underlaying dialog is closed after the new one is open

Follow this case:

1. open first dialog (from link or button)

2. open second dialog (from button from previous dialog) and close first dialog via 'close' command

3. close second dialog (via closing button)

3. try open first dialog again and stack trace will occur saying "Uncaught TypeError: Cannot read property '_focusTabbable' of undefined"

Workaround: close first dialog first then open a new one.

Tested on: latest Chrome and Firefox

Code example:

<script>
$(function() { 

   $("#link_test1").on('click', function() {
     $("#test_dlg1").dialog('open');
   });

   $("#test_dlg2").dialog({
      autoOpen: false,
      modal: true
   });

   $("#test_dlg1").dialog({
      autoOpen: false,
      modal: true,
      buttons: [
    		{
          text: "open",
 	  click: function() {
            $('#test_dlg2').dialog("open");
            $(this).dialog("close");
    			}
    		}
        ]
   });

});
</script>

<a href="#" id="link_test1">open</a>

<div id="test_dlg1" title="test1">
test1
</div>

<div id="test_dlg2" title="test2">
test2
</div>