Menu Customizer: page->panel in CSS.

git-svn-id: https://plugins.svn.wordpress.org/menu-customizer/trunk@939343 b8457f37-d9ea-0310-8a92-e5e31aec5664
Menu Customizer: revert to old added-item fadeIn for now.

git-svn-id: https://plugins.svn.wordpress.org/menu-customizer/trunk@939345 b8457f37-d9ea-0310-8a92-e5e31aec5664