PPC: Make --always-opt also optimize top-level code.

PPC: Make --always-opt also optimize top-level code.

Port 2d281e71ac49058ef5696f4255ff1fa30796bc5e

Original commit message:
This enables eager optimization of top-level code with TurboFan and
extends test coverage by triggering it with the --always-opt flag.
Script contexts are now also properly allocated in TurboFan.

R=titzer@chromium.org, mstarzinger@chromium.org,mbrandy@us.ibm.com
BUG=

Committed: https://crrev.com/5110b400bfc5f5e3f22b74b5dfb8261f60d422e2
Cr-Commit-Position: refs/heads/master@{#27726}

[michael_dawson, 2015-04-09 21:31:29]

Catching up, next ppc port

[Michael Starzinger, 2015-04-09 21:32:09]

LGTM.

[michael_dawson, 2015-04-09 21:48:16]

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

[commit-bot: I haz the power, 2015-04-09 21:48:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1052123005/1

[commit-bot: I haz the power, 2015-04-09 22:14:34]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-09 22:14:47]

Patchset 1 (id:??) landed as
https://crrev.com/5110b400bfc5f5e3f22b74b5dfb8261f60d422e2
Cr-Commit-Position: refs/heads/master@{#27726}