Set the secure flag on the wp-saving-post cookie when using HTTPS.

This cookie doesn't contain any sensitive information, but this change brings its behaviour in line with all other core cookies.

Fixes #31056

Built from https://develop.svn.wordpress.org/trunk@34027


git-svn-id: http://core.svn.wordpress.org/trunk@33996 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/autosave.js

@@ -286,7 +286,8 @@ window.autosave = function() {
 						});
 					}
 
-					wpCookies.set( 'wp-saving-post', post_id + '-check', 24 * 60 * 60 );
+					var secure = ( 'https:' === window.location.protocol );
+					wpCookies.set( 'wp-saving-post', post_id + '-check', 24 * 60 * 60, false, false, secure );
 				});
 			}