[2.1-beta-2] Fix product details meta box tabs for small width screens

On smaller screens, the tabs on the Product Data meta box were blank. This fixes the issue, and displays only the image on the tab, which I assume is the intended behaviour on small screens. See before and after screenshots below:

![tabs-broken](https://f.cloud.github.com/assets/148775/1713879/976e0c6c-6195-11e3-844f-3e878638fd43.png)

![tabs-fixed](https://f.cloud.github.com/assets/148775/1713880/9bebf862-6195-11e3-8171-0a707f601ead.png)