Ticket #28608: 28608.2.patch

admin-bar.css

@@ -105 +105 @@
    :hover states on an element that touches the extreme
    top left corner of the viewport. See #18868 */
 #wpadminbar .quicklinks {
-        border-left: 1px solid transparent;
+        /*border-left: 1px solid transparent;*/
 }
 
 #wpadminbar .quicklinks ul {