Revert of LayoutDescriptor should inherit from JSTypedArray

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
Committed: https://crrev.com/8a309a1eaedd8034d6b60908c01a0d188bceee1d
Cr-Commit-Position: refs/heads/master@{#27968}

[jochen (gone - plz use gerrit), 2015-04-21 14:02:50]

Created Revert of LayoutDescriptor should inherit from JSTypedArray

[commit-bot: I haz the power, 2015-04-21 14:02:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1073053006/1

[commit-bot: I haz the power, 2015-04-21 14:03:16]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-22 04:10:11]

Patchset 1 (id:??) landed as
https://crrev.com/8a309a1eaedd8034d6b60908c01a0d188bceee1d
Cr-Commit-Position: refs/heads/master@{#27968}