set_site_for_cookies
Description:
Sets site_for_cookies as the policy URL for same-site cookies for this.
It is either the URL of the top-level document or null depending on whether the registrable domain of this document's URL matches the registrable domain of its parent's/opener's URL. For the top-level document it is set to the document's URL.
See the same-site spec for more information.
Parameters:
| this | a Message | 
| site_for_cookies | the Uri for the this's site for cookies |