Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 22133)
+++ wp-includes/functions.php	(working copy)
@@ -251,18 +251,17 @@
 	$data = trim( $data );
  	if ( 'N;' == $data )
 		return true;
-	$length = strlen( $data );
-	if ( $length < 4 )
+	if ( strlen( $data ) < 4 )
 		return false;
 	if ( ':' !== $data[1] )
 		return false;
-	$lastc = $data[$length-1];
+	$lastc = substr( $data, -1 );
 	if ( ';' !== $lastc && '}' !== $lastc )
 		return false;
 	$token = $data[0];
 	switch ( $token ) {
 		case 's' :
-			if ( '"' !== $data[$length-2] )
+			if ( '"' !== substr( $data, -2, 1 ) )
 				return false;
 		case 'a' :
 		case 'O' :
@@ -288,16 +287,15 @@
 	if ( !is_string( $data ) )
 		return false;
 	$data = trim( $data );
-	$length = strlen( $data );
-	if ( $length < 4 )
+	if ( strlen( $data ) < 4 )
 		return false;
 	elseif ( ':' !== $data[1] )
 		return false;
-	elseif ( ';' !== $data[$length-1] )
+	elseif ( ';' !== substr( $data, -1 ) )
 		return false;
 	elseif ( $data[0] !== 's' )
 		return false;
-	elseif ( '"' !== $data[$length-2] )
+	elseif ( '"' !== substr( $data, -2, 1 ) )
 		return false;
 	else
 		return true;