This no longer causes allocation, so it's safe to unhandlify.

This will allow us to use directly call into C++ (via CallCFunction)
to calculate the hash instead of going through the runtime (via
%GenericHash).

Bug: v8:5717
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Ia561efb4d89d7a3d10c28913537b45b3ce477bb3
Reviewed-on: https://chromium-review.googlesource.com/624519Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47489}