PPC: Switch CallConstructStub to take new.target in register.

PPC: Switch CallConstructStub to take new.target in register.

Port 1d9d895754e1d1cf824c11a9cce5e495fa47d5e2

Original commit message:
    This changes the calling convention of the CallConstructStub to take
    the original constructor (i.e. new.target in JS-speak) in a register
    instead of magically via the operand stack. For optimizing compilers
    the operand stack doesn't exist, hence cannot be peeked into.

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

Committed: https://crrev.com/a02f7e6f496976f960d37125ffeab3dc2983ce9a
Cr-Commit-Position: refs/heads/master@{#29702}

[Michael Starzinger, 2015-07-16 07:34:37]

LGTM.

[MTBrandyberry, 2015-07-16 12:34:11]

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

[commit-bot: I haz the power, 2015-07-16 12:34:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1230103004/1

[commit-bot: I haz the power, 2015-07-16 12:59:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-16 13:00:01]

Patchset 1 (id:??) landed as
https://crrev.com/a02f7e6f496976f960d37125ffeab3dc2983ce9a
Cr-Commit-Position: refs/heads/master@{#29702}

[dstence, 2015-07-16 13:48:12]

lgtm