PPC: New hydrogen instruction to reduce cost of growing an array on keyed stores.

PPC: New hydrogen instruction to reduce cost of growing an array on keyed stores.

Port 3bce9c3afbe792167a54db49b16679289e0aea8f

Original commit message:
HMaybeGrowElements moves the situation where you actually have to grow
into deferred code. This means crankshaft doesn't have to spill registers
just to make the bounds comparison to see if it'll need to grow or not.

It makes the growing case a bit more expensive, but reduces the cost of
the general case.

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

Committed: https://crrev.com/09ecf6cef7f24169ab74bac4c4c4f4459d3d4df4
Cr-Commit-Position: refs/heads/master@{#28372}

[dstence, 2015-05-12 15:05:31]

lgtm

[MTBrandyberry, 2015-05-12 15:06:47]

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

[commit-bot: I haz the power, 2015-05-12 15:06:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1132743004/1

[commit-bot: I haz the power, 2015-05-12 15:42:48]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-12 15:42:51]

Patchset 1 (id:??) landed as
https://crrev.com/09ecf6cef7f24169ab74bac4c4c4f4459d3d4df4
Cr-Commit-Position: refs/heads/master@{#28372}