Turns off textarea wrapping in a cross-browser compliant way

The previous CSS-based approach didn’t work in Firefox. The new approach uses the `wrap` attribute instead, which does.

Before:
![screen shot 2014-11-18 at 3 35 14 pm](https://cloud.githubusercontent.com/assets/186715/5098215/864449a4-6f38-11e4-9f98-fd873cb1f028.png)

After:
![screen shot 2014-11-18 at 3 35 01 pm](https://cloud.githubusercontent.com/assets/186715/5098217/88f20448-6f38-11e4-9cb4-e170c5e28067.png)