This allows us to remove the loop while calculating the hash value and
just use the HashMask as the mask for ComputeIntegerHash. This
previously overflowed on 32-bit systems failing the Smi::IsValid
check.

Bug: v8:6404
Change-Id: I84610a7592fa9d7ce4fa5cef7903bd50b8e8a4df
Reviewed-on: https://chromium-review.googlesource.com/702675Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48319}