This site seems to be a tough test for Webkit. I am using build r37698 and animation looping no longer works. Page renders very quickly.
Confirmed. There is something wrong with GIF animation in WebKit. The animation after first loading doesn't start but after restarting WebKit and loading the site from cache gif starts animating.
Opening image in new tab also causes WebKit to start GIF animation on a new tab.
*** This bug has been marked as a duplicate of 22995 ***