They can no longer return nan. They basically intersect their argument
type with Type::OrderedNumber before analysing it. Never call them on
Type::NaN.

Bug: 
Change-Id: I7e7b46aa9fcde4f2644b81b3a34e76b092f633a4
Reviewed-on: https://chromium-review.googlesource.com/763410
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49375}