Widgets: Add click-to-add widgets to the bottom (not top) of the target sidebar.

fixes #25821.

Built from https://develop.svn.wordpress.org/trunk@26696


git-svn-id: http://core.svn.wordpress.org/trunk@26586 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/widgets.js

@@ -433,7 +433,7 @@ wpWidgets = {
 		// Open the widgets container
 		sidebar.closest( '.widgets-holder-wrap' ).removeClass('closed');
 
-		sidebar.find('.sidebar-description').after( widget );
+		sidebar.append( widget );
 		sidebar.sortable('refresh');
 
 		wpWidgets.save( widget, 0, 0, 1 );