Implementation of anyfunc parameters. Different to anyref parameters we
have to do a validation in the js-to-wasm wrapper: Only exported wasm
functions are allowed. I implemented this check in a runtime function.

R=titzer@chromium.org

Bug: v8:7581
Change-Id: I6145782fb8578124ddc21b50133c82235d666f19
Reviewed-on: https://chromium-review.googlesource.com/c/1417470Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58885}