This removes two shortcuts ("UndefinedValue" and "NullValue") from the
instance object and instead loads those values via the root set which is
also referenced from the instance. It makes instance objects smaller.

Note that this also contains an optimization to make sure "undefined" is
only loaded once and then re-used within a single wrapper.

R=clemensh@chromium.org

Change-Id: I421f202230e91790fa9c8263770b4e4bbd3c47bd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1710670Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62860}