This is a reland of 942c61ab
Original change's description:
> [runtime] Rename PropertyArray::kLengthOffset to kLengthAndHashOffset
> 
> LengthAndHashOffset describes the value stored in the offset better.
> 
> Bug: v8:6404
> Change-Id: Ie5ea2a362c54aa03e0a4e314d1adb8b91d74a044
> Reviewed-on: https://chromium-review.googlesource.com/624458
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#47503}

TBR=jkummerow@chromium.org, mstarzinger@chromium.org

Bug: v8:6404
Change-Id: Ied55fa6145ccc788581703db991b2f78d59a7408
Reviewed-on: https://chromium-review.googlesource.com/627075Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47530}