It’s a security thing
That returns a Response Header
alt-svc:quic=":443"; ma=2592000; v="35,34"
cache-control:no-cache, no-store, max-age=0, must-revalidate
content-encoding:gzip
content-type:text/html; charset=utf-8
date:Tue, 31 Jan 2017 19:45:19 GMT
expires:Mon, 01 Jan 1990 00:00:00 GMT
pragma:no-cache
server:GSE
status:200
x-content-type-options:nosniff
x-frame-options:SAMEORIGIN
x-robots-tag:noindex, nofollow, nosnippet
x-xss-protection:1; mode=block
The SAMEORIGIN bit
SAMEORIGIN
The page can only be displayed in a frame on the same origin as the page itself.