Include API-instantiated functions in the definition of Callable so
that PromiseReactionJobTask::handler can verify correctly. Also make
Callable verification stricter regarding JSProxy instances: they must
have the callable bit set.

Also update test-weak-references to use a different object type, since
FeedbackVector::optimized_code_weak_or_smi should never point to a
FixedArray.

Bug: v8:9311
Change-Id: I4242df993e381a75f5b53302fee8fd2b12e96d34
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1650563
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62153}