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

On narrow screens, tabs on the Product Data meta box are blank. This fixes the issue, and displays only the image on the tab, which I assume is the intended behaviour. 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)