Index: wp-includes/css/admin-bar.css
===================================================================
--- wp-includes/css/admin-bar.css	(revision 23946)
+++ wp-includes/css/admin-bar.css	(working copy)
@@ -13,6 +13,10 @@
 	-webkit-box-sizing: content-box;
 	-moz-box-sizing:    content-box;
 	box-sizing:         content-box;
+	-webkit-transition: none;
+	-moz-transition:    none;
+	-o-transition:      none;
+	transition:         none;
 }
 
 #wpadminbar ul li:before,