Merge pull request #4762 from tianhe1986/develop_cache_file_metadata

Cache_file: use $data['time'] for calculating expired time.
diff --git a/system/libraries/Cache/drivers/Cache_file.php b/system/libraries/Cache/drivers/Cache_file.php
index f579eaa..93932d4 100644
--- a/system/libraries/Cache/drivers/Cache_file.php
+++ b/system/libraries/Cache/drivers/Cache_file.php
@@ -227,13 +227,13 @@
 		{
 			$mtime = filemtime($this->_cache_path.$id);
 
-			if ( ! isset($data['ttl']))
+			if ( ! isset($data['ttl'], $data['time']))
 			{
 				return FALSE;
 			}
 
 			return array(
-				'expire' => $mtime + $data['ttl'],
+				'expire' => $data['time'] + $data['ttl'],
 				'mtime'	 => $mtime
 			);
 		}