Revert of LayoutDescriptor should inherit from JSTypedArray (patchset #1 id:1 of https://codereview.chromium.org/1084793004/)

Reason for revert:
breaks mjsunit on debug bots

Original issue's description:
> LayoutDescriptor should inherit from JSTypedArray
>
> It can't just inherit from a FixedTypedArray-like type, as we soon
> assume that a FixedTypedArray-like type is always held by an
> ArrayBufferView-like type
>
> BUG=v8:3996
> R=ishell@chromium.org,verwaest@chromium.org
> LOG=n

TBR=ishell@chromium.org,verwaest@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:3996

Review URL: https://codereview.chromium.org/1073053006

Cr-Commit-Position: refs/heads/master@{#27968}