PPC: Reshuffle registers in JSConstructStub to avoid trashing costructor and new.target on fast pat…

PPC: Reshuffle registers in JSConstructStub to avoid trashing costructor and new.target on fast path (so we don't need to push/pop them).

Port 0ef5ad5ab97657f7e3393be7512fef883b205c87

Original commit message:
    This CL also fixed register usages in MacroAssembler::Allocate() broken by 2fc2cb99 (r32144).

R=ishell@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=chromium:560239
LOG=Y

Committed: https://crrev.com/9b3dff93ad8ddf616298bf7be4a37450728158b2
Cr-Commit-Position: refs/heads/master@{#32230}

[MTBrandyberry, 2015-11-24 20:00:28]

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

[commit-bot: I haz the power, 2015-11-24 20:00:41]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1472823004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1472823004/1

[commit-bot: I haz the power, 2015-11-24 20:58:41]

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

[commit-bot: I haz the power, 2015-11-24 20:58:41]

Dry run: This issue passed the CQ dry run.

[michael_dawson, 2015-11-24 21:14:09]

On 2015/11/24 20:58:41, commit-bot: I haz the power wrote:
> Dry run: This issue passed the CQ dry run.

lgtm

[MTBrandyberry, 2015-11-24 21:25:10]

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

[commit-bot: I haz the power, 2015-11-24 21:25:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1472823004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1472823004/1

[commit-bot: I haz the power, 2015-11-24 21:27:39]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-24 21:27:49]

Patchset 1 (id:??) landed as
https://crrev.com/9b3dff93ad8ddf616298bf7be4a37450728158b2
Cr-Commit-Position: refs/heads/master@{#32230}