PPC: HydrogenCodeStubs consume stack arguments via descriptor.

PPC: HydrogenCodeStubs consume stack arguments via descriptor.

Port 3334b830a512eda1f8eed678a0e6fda52b23472a

Original commit message;
    All of this is controlled by the CallDescriptor. It's simply the case
    that if you specify less registers than the function arity calls for,
    the rest are assumed to be on the stack.

    Bailout handlers accept these constant stack arguments too.

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

Committed: https://crrev.com/f80e6869063140f0684cea498b8687bd99332d61
Cr-Commit-Position: refs/heads/master@{#29820}

[dstence, 2015-07-23 15:45:00]

lgtm

[MTBrandyberry, 2015-07-23 15:50:53]

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

[commit-bot: I haz the power, 2015-07-23 15:51:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1256563002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1256563002/1

[commit-bot: I haz the power, 2015-07-23 16:17:22]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-23 16:17:34]

Patchset 1 (id:??) landed as
https://crrev.com/f80e6869063140f0684cea498b8687bd99332d61
Cr-Commit-Position: refs/heads/master@{#29820}