Reverting Firefox Windows bug fix ipython/ipython#8853

This effectively cloned all of the pager DOM nodes and removed
all of their events. This broke the pager closing and resizing.

notebook/static/notebook/js/pager.js

@@ -78,11 +78,6 @@ define([
                 // This allows the pager-contents div to use percentage sizing.
                 that.pager_element.height(that.pager_element.height());
                 that._resize();
-                
-                // Fixes: ipython/ipython#8853
-                // Horrible hack that forces firefox to recalculate the content 
-                // size so the scrollbars get rendered.
-                that.pager_element.html(that.pager_element.html());
             });
         });