[cairo] Division by zero in cairo-ft-font.c

[Jason Dorje Short]

Owen Taylor wrote:
> Turns out that loading a size zero font was causing badness:
> 
>  http://bugzilla.gnome.org/show_bug.cgi?id=311299
> 
> Absolutley huge (700M+) surfaces were  being created for glyphs,
> etc.
> 
> I put in a pretty quick fix, attached below. I'm not absolutely
> sure that there aren't still problems with near zero fonts, but
> being late on a Friday, I just wanted to get something in that
> would stop the problems.

What about negative-sized fonts?

-jason