Properly handle backslashes in regexes

Noticed an issue when having a regex of just `/\\/`.

### Before

![screen shot 2013-11-02 at 7 01 58 pm](https://f.cloud.github.com/assets/671378/1460340/514b6878-442c-11e3-9e89-17f982307874.png)

### After

![screen shot 2013-11-02 at 7 06 04 pm](https://f.cloud.github.com/assets/671378/1460345/9bc4a34c-442c-11e3-9bb1-04349f4fa10a.png)