With this CL it is possible to import any JavaScript object as an anyref
global. The exception is WasmGlobalObject, which cannot hold anyref
globals yet.

R=clemensh@chromium.org

Bug: v8:7581
Change-Id: I5b0fc686a4ec5c579d1d635b53be5ccdf0a78f27
Reviewed-on: https://chromium-review.googlesource.com/c/1382452
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58557}