This makes the WebAssembly function constructor return a proper function
object. Note that the returned object is not yet callable, only the
prototype structure is in place.

R=jkummerow@chromium.org
TEST=mjsunit/wasm/type-reflection
BUG=v8:7742

Change-Id: If6a3d0ae7078b5526606eef1b8fd4815353b850b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627343
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61792}