PPC: VectorICs: use a vector slot to aid in array literal processing.

PPC: VectorICs: use a vector slot to aid in array literal processing.

Port f2f46aff8b776365e0bafd7826f23c8b9c16d928

Original commit message:
    The lack of a vector slot for the keyed store operation in filling in
    non-constant array literal properties led to undesirable contortions in
    compilers downwind of full-codegen. The use of a single slot to initialize all
    the array elements is sufficient.

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/0f51a3506191ea77269a5aae53d13dc6e4043b94
Cr-Commit-Position: refs/heads/master@{#31261}

[MTBrandyberry, 2015-10-13 22:30:39]

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

[commit-bot: I haz the power, 2015-10-13 22:30:56]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1390353006/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1390353006/1

[michael_dawson, 2015-10-13 22:39:12]

On 2015/10/13 22:30:56, 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/1390353006/1
> View timeline at
>  https://chromium-cq-status.appspot.com/patch-timeline/1390353006/1

lgtm

[commit-bot: I haz the power, 2015-10-13 22:52:40]

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

[commit-bot: I haz the power, 2015-10-13 22:52:41]

Dry run: This issue passed the CQ dry run.

[MTBrandyberry, 2015-10-14 13:16:41]

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

[commit-bot: I haz the power, 2015-10-14 13:16:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1390353006/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1390353006/1

[commit-bot: I haz the power, 2015-10-14 13:18:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-14 13:18:41]

Patchset 1 (id:??) landed as
https://crrev.com/0f51a3506191ea77269a5aae53d13dc6e4043b94
Cr-Commit-Position: refs/heads/master@{#31261}