PPC: Introduce LiteralsArray to hide it's implementation.

PPC: Introduce LiteralsArray to hide it's implementation.

Port d8cdd6956a04cfcf03159ef7802c44838eee3146

Original commit message:
    The LiteralsArray will soon hold a type feedback vector. Code treats it as an
    ordinary fixed array, and needs to stop that.

R=mvstanton@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=

Committed: https://crrev.com/aeefe1013d268a1c8df7ac17e8b09fbbca90cc6e
Cr-Commit-Position: refs/heads/master@{#31035}

[MTBrandyberry, 2015-09-30 20:28:53]

The CQ bit was checked by mbrandy@us.ibm.com to run a CQ dry run

[commit-bot: I haz the power, 2015-09-30 20:29:02]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1373823003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1373823003/1

[michael_dawson, 2015-09-30 20:54:50]

On 2015/09/30 20:29:02, commit-bot: I haz the power wrote:
> Dry run: CQ is trying da patch. Follow status at
>  https://chromium-cq-status.appspot.com/patch-status/1373823003/1
> View timeline at
>  https://chromium-cq-status.appspot.com/patch-timeline/1373823003/1

lgtm.

[commit-bot: I haz the power, 2015-09-30 21:03:06]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-30 21:03:07]

Dry run: This issue passed the CQ dry run.

[MTBrandyberry, 2015-09-30 21:07:52]

The CQ bit was checked by mbrandy@us.ibm.com

[commit-bot: I haz the power, 2015-09-30 21:08:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1373823003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1373823003/1

[commit-bot: I haz the power, 2015-09-30 21:10:26]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-30 21:10:43]

Patchset 1 (id:??) landed as
https://crrev.com/aeefe1013d268a1c8df7ac17e8b09fbbca90cc6e
Cr-Commit-Position: refs/heads/master@{#31035}