Index: wp-includes/css/editor.css
===================================================================
--- wp-includes/css/editor.css	(revision 21626)
+++ wp-includes/css/editor.css	(working copy)
@@ -2033,7 +2033,7 @@
 	border-width: 1px;
 	border-top-left-radius: 0;
 	border-top-right-radius: 3px;
-	border-bottom-right-left: 0;
+	border-bottom-left-radius: 0;
 	border-bottom-right-radius: 3px;
 }