Revert "Add Session::abort_save() to Kohana."

Obsoleted by upstream fix.

This reverts commit 06f066164f.

system/libraries/drivers/Session/Database.php

@@ -98,10 +98,6 @@ class Session_Database_Driver implements Session_Driver {
 
 	public function write($id, $data)
 	{
-                if (!Session::$should_save) {
-                        return true;
-                }
-
 		$data = array
 		(
 			'session_id' => $id,