With this CL we now also support the decoding of the AnyFunc
type. I will add the type more deeply in subsequent CLs.

R=titzer@chromium.org

Bug: v8:7581
Change-Id: I9f30706a442462f915adfd8f720eb65168b80bb8
Reviewed-on: https://chromium-review.googlesource.com/1014111
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54318}