This new function forwards to v8::Object::CreationContext but has
special handling for JSGlobalProxy objects to prevent the former from
crashing.

R=yangguo@chromium.org

Bug: chromium:952057
Change-Id: I5ade682976efd1724c13f52b468e4fb30bb9ade7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1569425
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61197}