[turbofan] Initial support for keyed access to holey elements.

[turbofan] Initial support for keyed access to holey elements.

This adds support for load/store access to FAST_HOLEY_ELEMENTS and
FAST_HOLEY_SMI_ELEMENTS backing stores. We don't currently fully support
the double holes, because we make some difficult assumptions in
Crankshaft there.

R=jarin@chromium.org
BUG=v8:4470
LOG=n

Committed: https://crrev.com/59ba2a8f34dfbeeb5625757f190df5720d3a8c4b
Cr-Commit-Position: refs/heads/master@{#32012}

[Benedikt Meurer, 2015-11-16 14:15:30]

Hey Jaro,

Here's the initial support for holey arrays. I'll refactor that stuff tomorrow
and split up the JSNativeContextSpecialization methods; but I wanted to get the
fundamentals in there first.
Please take a look.

Thanks,
Benedikt

[Jarin, 2015-11-16 15:49:21]

lgtm. (Yes, this is harder to read than Crankshaft at the moment, please
refactor.)

[Benedikt Meurer, 2015-11-16 16:21:14]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-11-16 16:21:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1448903002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1448903002/1

[commit-bot: I haz the power, 2015-11-16 16:46:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-16 16:47:05]

Patchset 1 (id:??) landed as
https://crrev.com/59ba2a8f34dfbeeb5625757f190df5720d3a8c4b
Cr-Commit-Position: refs/heads/master@{#32012}