Possible to capture response headers when page finishes loading?

I would like to get the headers of the http response we get back. It seems that we can the the url, cookies, user agent (by evaluating javascript), and the html string (again, by evaluating javascript), but we don't even get access to the response object itself, which makes getting headers impossible. Is there a way to do it, or plan to support it in the future? I believe in native webviews we can access the headers.