Don't pre-fill empty image alt when inserting into a post.

git-svn-id: https://develop.svn.wordpress.org/trunk@12161 602fd350-edb4-49c9-b593-d223f7449a82

wp-admin/css/media.dev.css

@@ -123,6 +123,10 @@ abbr.required {
 	padding: 0 5px 8px 0;
 }
 
+.describe td.error {
+	padding: 2px 8px;
+}
+
 .describe td.A1 {
 	width: 132px;
 }