ability to open admin windows in iframes inside windows

[fool]

- Do you want to request a feature or report a bug?

bug

- What is the current behavior?

ability to duplicate the admin iframe inside of the admin screen (see screenshots)

- If the current behavior is a bug, please provide the steps to reproduce.

begin a new blog post, click in the empty preview on the headline-card for the post before doing anything else.

- What is the expected behavior?

unable to load the admin in an iframe already inside the admin

- Please mention your node.js, and operating system version.

this was observed on the site running from a static server. It was built using Node.js v 6.9.1 on ubuntu14.04 (netlify buildbots).

[fool]

screenshots: