WP_HTTP: Enable developers to request the first x bytes of a document using the 'limit-response-size' parameter.
The connection to the remote server will be disconnected after x number of bytes has been received.
See #23472


git-svn-id: http://core.svn.wordpress.org/trunk@23605 1a063a9b-81f0-0310-95a4-ce76da25c4cd