This reverts commit 942c61ab.

Reason for revert: compile failures (mid-air conflict with another cl)

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,gsathya@chromium.org

Change-Id: I4b439323ab5b328cd8f29908b35eeddffdf5b141
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6404
Reviewed-on: https://chromium-review.googlesource.com/626076
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47505}