--- a/wp-includes/post-template.php
+++ b/wp-includes/post-template.php
@@ -324,26 +324,10 @@
 		}
 	}
 
-	if ( $preview ) // Preview fix for JavaScript bug with foreign languages.
-		$output =	preg_replace_callback( '/\%u([0-9A-F]{4})/', '_convert_urlencoded_to_entities', $output );
-
 	return $output;
 }
 
 /**
- * Preview fix for JavaScript bug with foreign languages.
- *
- * @since 3.1.0
- * @access private
- *
- * @param array $match Match array from preg_replace_callback.
- * @return string
- */
-function _convert_urlencoded_to_entities( $match ) {
-	return '&#' . base_convert( $match[1], 16, 10 ) . ';';
-}
-
-/**
  * Display the post excerpt.
  *
  * @since 0.71
