fix(client): Allow Fx18 to use the iframe flow.


Fx18 had two problems:
1) anchor.origin is not available and must be built from anchor.protocol and anchor.host.
2) anchor.protocol and anchor.host are only updated if the anchor's href is set via `anchor.setAttribute(href, ...`.

fixes #1969


![screen shot 2014-12-10 at 11 39 15](https://cloud.githubusercontent.com/assets/848085/5375476/7237cdce-8062-11e4-8dc3-6b67665d717c.png)