Fixed nonbreakable space in CSS

I've upgraded Nette on one of my project and I noticed some weird question marks in tracy dumps (see screenshot below). I've already seen a bug report with this but can't find it now. Anyway it seems it's not fixed yet.

![bug](https://cloud.githubusercontent.com/assets/539462/5061684/bca7c0ea-6da1-11e4-8f3c-d38a7a21506d.png)