To a rendering engine, this isn't any simpler or more complex than any other page. The reason we see this bug is probably that something in the page takes a code path that is taken very seldom, and thus has not been discovered before.
I'm not saying it's ok to have this bug, just that it doesn't really make sense to come up with a small testcase and say "How can you break something so simple?".
I reported a bug, by the way.