Revert 158466 "'X-Frame-Options: SAMEORIGIN' should check all an..."

This CL caused:

Cannot insert Google Slides into a Google Sites page
https://code.google.com/p/chromium/issues/detail?id=305244

> 'X-Frame-Options: SAMEORIGIN' should check all ancestor frames.
> 
> Currently, XFO performs a same origin check only against the top-level
> frame in a document's ancestor chain. As lcamtuf notes in [1], "Any site
> that allows a rogue ad to be displayed in an IFRAME; or that frames
> third-party content for other reasons (e.g., iGoogle, Image Search
> results, Facebook gadgets), is effectively not protected, because the
> framed content from evil.com can load and arbitrarily decorate any page
> in the same origin as the top-level window, and entice the user to
> interact with it."
> 
> This patch adjusts Blink's behavior to check each of a document's
> ancestors, and blocks the load if any aren't same-origin with the
> document being loaded.
> 
> [1]: https://bugzilla.mozilla.org/show_bug.cgi?id=725490
> 
> BUG=250309
> 
> Review URL: https://chromiumcodereview.appspot.com/20822002

TBR=mkwst@chromium.org

Review URL: https://codereview.chromium.org/61773006

git-svn-id: svn://svn.chromium.org/blink/trunk@161477 bbb929c8-8fbe-4397-9dbb-9b2b20218538