This is so that we can distinguish hash tables by instance type. We can
then introduce maps for each kind of hash tables to further distinguish.

R=mstarzinger@chromium.org

Bug: v8:6593
Change-Id: Ice9e6bb7b85d825207ac489b6930ac9020d60db8
Reviewed-on: https://chromium-review.googlesource.com/582814Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46861}