Throw an exception when accessing 'window.open' and 'window.opener' cross-origin.

Gecko throws on both of these; we should do the same.

BUG=17325

Review URL: https://chromiumcodereview.appspot.com/22865016

git-svn-id: svn://svn.chromium.org/blink/trunk@156554 bbb929c8-8fbe-4397-9dbb-9b2b20218538