fix bug Warning: array_slice() expects parameter 1 to be array, null given in /www/public_html/blog/wp-content/plugins/wp2pcs/hook/insert-media.php on line 108

git-svn-id: https://plugins.svn.wordpress.org/wp2pcs/trunk@1045008 b8457f37-d9ea-0310-8a92-e5e31aec5664