This CL adds initial tests for the tier-up logic.

Change-Id: I6e6ff69604b14387e81b08d178f98d2227b4f496
Bug: v8:9566
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1776080
Commit-Queue: Ana Pesko <anapesko@google.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63503}