Restoring previous revision of PDF document results in conflicting styles

Restoring a previous revision of a PDF document injects that revision's CSS style sheets, but it doesn't remove the (now out of date) style sheets from the revision first shown on the page. This can result in a garbled display.

![screen shot 2014-05-08 at 11 24 43 am](https://cloud.githubusercontent.com/assets/1731910/2917378/75fc4be8-d6c5-11e3-889d-24f4fc678f71.png)

Refreshing the page fixes the display

![screen shot 2014-05-08 at 11 26 11 am](https://cloud.githubusercontent.com/assets/1731910/2917386/84634da8-d6c5-11e3-9a64-0e22c24e4311.png)