Fixes a notice on post-new.php Notice: Trying to get property of non-object in wp-content/plugins/jetpack/modules/gplus-authorship/admin/ui.php on line 207
Check for exitence of $post by trying to access data from it.


git-svn-id: https://plugins.svn.wordpress.org/jetpack/trunk@773454 b8457f37-d9ea-0310-8a92-e5e31aec5664