Image filter: compare aspect ratio more accurately during crop.
Image filter: compare aspect ratio more accurately during crop.

Previously used fixed-point calculation caused wrong code path selection
in some cases, resulting in incorrect image size.

See here for report:
http://mailman.nginx.org/pipermail/nginx-devel/2012-April/002123.html

firebase/nginx,hy0kl/nginx,firebase/nginx,firebase/nginx,hy0kl/nginx,hy0kl/nginx,firebase/nginx