make close-and-halt work on new tabs in Chrome

this is not possible in Firefox, as new tabs/windows which were *not*
opened via a script ( window.open call ) are not allowed to be closed
via window.close and will yield a message like

--
[11:50:59.691] Scripts may not close windows that were not opened by script. @ http://localhost:8888/static/notebook/js/menubar.js:105

IPython/html/static/notebook/js/menubar.js

@@ -131,7 +131,11 @@ var IPython = (function (IPython) {
         });
         this.element.find('#kill_and_exit').click(function () {
             IPython.notebook.session.delete();
-            setTimeout(function(){window.close();}, 500);
+            setTimeout(function(){
+                // allow closing of new tabs in Chromium, impossible in FF
+                window.open('', '_self', '');
+                window.close();
+            }, 500);
         });
         // Edit
         this.element.find('#cut_cell').click(function () {