Index: src/wp-includes/js/quicktags.js
===================================================================
--- src/wp-includes/js/quicktags.js	(revision 29770)
+++ src/wp-includes/js/quicktags.js	(working copy)
@@ -247,7 +247,7 @@
 			defaults = ',strong,em,link,block,del,ins,img,ul,ol,li,code,more,close,';
 
 		for ( inst in t.instances ) {
-			if ( inst === 0 ) {
+			if ( '0' === inst ) {
 				continue;
 			}
 
@@ -323,7 +323,7 @@
 	 * @param string access_key Optional. Access key for the button.
 	 * @param string title Optional. Button's title="..."
 	 * @param int priority Optional. Number representing the desired position of the button in the toolbar. 1 - 9 = first, 11 - 19 = second, 21 - 29 = third, etc.
-	 * @param string instance Optional. Limit the button to a specifric instance of Quicktags, add to all instances if not present.
+	 * @param string instance Optional. Limit the button to a specific instance of Quicktags, add to all instances if not present.
 	 * @return mixed null or the button object that is needed for back-compat.
 	 */
 	qt.addButton = function( id, display, arg1, arg2, access_key, title, priority, instance ) {