Calling a multi-return WASM function from JS creates an array filled
with the returned values.

See: https://github.com/WebAssembly/multi-value

R=ahaas@chromium.org

Bug: v8:9492
Change-Id: I3151212b6784782c8f89908befab9d26b32e5a8b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1739372
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63110}