Introduce X-Frame-Origin header

Change-Id: Ia9b66297c68f819b26158c79fb2da6572c784898
diff --git a/t/page.t b/t/page.t
index 88479f5..c9bce7f 100644
--- a/t/page.t
+++ b/t/page.t
@@ -33,6 +33,7 @@
   ->content_like(qr/document\.body\.classList\.remove\(\'no-js\'\);/)
   ->header_is('X-Content-Type-Options', 'nosniff')
   ->header_is('Access-Control-Allow-Methods','GET, POST, OPTIONS')
+  ->header_is('X-Frame-Options', 'sameorigin')
   ;
 
 # Test additions