PPC: [es6] Spread in array literals

PPC: [es6] Spread in array literals

Port 9502e91adbed48a546463aa848656d07619d14e6

Original commit message:
This allows you to put iterables into your array literals
and the will get spread into the array.

  let x = [0, ...range(1, 3)];  // [0, 1, 2]

This is done by treating the array literal up to the first
spread element as usual, including using a boiler plate
array, and then appending the remaining expressions and rest
expressions.

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

Committed: https://crrev.com/fc146e9e91350eb455e1a5bc71c46733413dd054
Cr-Commit-Position: refs/heads/master@{#28560}

[dstence, 2015-05-21 14:56:15]

lgtm

[MTBrandyberry, 2015-05-21 15:08:22]

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

[commit-bot: I haz the power, 2015-05-21 15:08:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1149873005/1

[commit-bot: I haz the power, 2015-05-21 15:35:53]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-21 15:36:04]

Patchset 1 (id:??) landed as
https://crrev.com/fc146e9e91350eb455e1a5bc71c46733413dd054
Cr-Commit-Position: refs/heads/master@{#28560}