Avoid a fatal error in WP_Http::request() if $response is a WP_Error instance. props dllh, nacin. fixes #24987.
Built from https://develop.svn.wordpress.org/trunk@25114


git-svn-id: http://core.svn.wordpress.org/trunk@25095 1a063a9b-81f0-0310-95a4-ce76da25c4cd