PPC: Vector-ICs - speed towards the monomorphic exit as quickly as possible.

PPC: Vector-ICs - speed towards the monomorphic exit as quickly as possible.

Port 35a67b745d862c5b1f584c2786ebf1369dc4f1ff

Original commit message:
Thanks to some careful assumptions, we can examine the object found at
vector[slot] and trust it's a heap object where the second field is
either a map if it's a WeakCell, or definitely not a map if it's a
Symbol, String or FixedArray. Use this to save a memory read.

R=mbrandy@us.ibm.com

BUG=

Committed: https://crrev.com/806e57f401bf3add4f9248931ef045c6bab7a995
Cr-Commit-Position: refs/heads/master@{#27728}

[michael_dawson, 2015-04-09 21:45:09]

Catching up, Next PPC port

[MTBrandyberry, 2015-04-09 21:47:09]

On 2015/04/09 21:45:09, michael_dawson wrote:
> Catching up, Next PPC port

lgtm

[michael_dawson, 2015-04-09 21:48:45]

The CQ bit was checked by michael_dawson@ca.ibm.com

[commit-bot: I haz the power, 2015-04-09 21:49:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1059133005/1

[commit-bot: I haz the power, 2015-04-09 22:32:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-09 22:32:32]

Patchset 1 (id:??) landed as
https://crrev.com/806e57f401bf3add4f9248931ef045c6bab7a995
Cr-Commit-Position: refs/heads/master@{#27728}