Fix typo in var definition in [28069], see #27750

Built from https://develop.svn.wordpress.org/trunk@28070


git-svn-id: http://core.svn.wordpress.org/trunk@27901 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/post.js

@@ -486,7 +486,7 @@ jQuery(document).ready( function($) {
 
 	// This code is meant to allow tabbing from Title to Post content.
 	$('#title').on( 'keydown.editor-focus', function( event ) {
-		var editor, textarea;
+		var editor, $textarea;
 
 		if ( event.keyCode === 9 && ! event.ctrlKey && ! event.altKey && ! event.shiftKey ) {
 			editor = typeof tinymce != 'undefined' && tinymce.get('content');