LayoutDescriptor should inherit from JSTypedArray

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

Committed: https://crrev.com/6d79ceb2945bc23a33ac5c93285a2cab2ba2e126
Cr-Commit-Position: refs/heads/master@{#27964}

[Igor Sheludko, 2015-04-21 12:50:18]

lgtm for now to unblock landing FixedTypedArray-ArrayBufferView relationship
changes. The proper way would be to add FixedUint32TypedArray-like array
instead. I'll do that early next week.

[jochen (gone - plz use gerrit), 2015-04-21 12:59:47]

The CQ bit was checked by jochen@chromium.org

[commit-bot: I haz the power, 2015-04-21 12:59:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1084793004/1

[commit-bot: I haz the power, 2015-04-21 13:07:36]

Committed patchset #1 (id:1)

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

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1073053006/ by jochen@chromium.org.

The reason for reverting is: breaks mjsunit on debug bots.

[commit-bot: I haz the power, 2015-04-22 04:09:58]

Patchset 1 (id:??) landed as
https://crrev.com/6d79ceb2945bc23a33ac5c93285a2cab2ba2e126
Cr-Commit-Position: refs/heads/master@{#27964}