- Use a builtin for the fast path of Wasm RefFunc.
- Simplify the runtime function by passing instance as first
  argument.

Change-Id: I5f6993cae21a878cee21a391a25c4d574243058b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2144533
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67346}