Agreed with @stof. The drivers, that don't know how to determine visibility like Zombie, Goutte and BrowserKit will also return an invisible text. This fact is documented (I hope), so this never caused a problem to anybody.

But if you (@robsquires), plan to add some tests to verify that visibility of elements is taken into account by the diver (without changing driver code), then only place them in `CSSDriverTest` class (after we merge it).