Fixed wrap issue with pre tags

Fixed wrap issue in pre tags in Firefox browsers. Firefox only wraps
content only if white-space value is normal.
![issue](https://f.cloud.github.com/assets/5234061/966933/2240af0e-055f-11e3-95ed-96ec0e1ebe7c.png)
![fixed](https://f.cloud.github.com/assets/5234061/966935/29383e6c-055f-11e3-9a13-d9ab38f8d34d.png)