Now that we no longer store the hash in the hash_code_symbol, we can
do a fast lookup on the kPropertiesOrHash offset instead.

Bug: v8:5717
Change-Id: I8724db3c9eb82c3f98aef650b54ae36b76fd12fd
Reviewed-on: https://chromium-review.googlesource.com/624377
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47491}