PPC: Make FlushICache part of Assembler(Base) and take Isolate as parameter.

PPC: Make FlushICache part of Assembler(Base) and take Isolate as parameter.

Port 9fc4fc141fa1d1aa1a3ccb901518cdffa0d6d268

R=mlippautz@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=chromium:524425
LOG=N

Committed: https://crrev.com/31026cd5a0e192b6b1f79f4b27bcbadca60c265e
Cr-Commit-Position: refs/heads/master@{#30698}

[MTBrandyberry, 2015-09-11 14:26:09]

The CQ bit was checked by mbrandy@us.ibm.com to run a CQ dry run

[commit-bot: I haz the power, 2015-09-11 14:26:13]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1339673002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1339673002/1

[commit-bot: I haz the power, 2015-09-11 15:04:03]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-11 15:04:04]

Dry run: This issue passed the CQ dry run.

[john.yan, 2015-09-11 15:06:55]

lgtm

[MTBrandyberry, 2015-09-11 15:07:19]

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

[commit-bot: I haz the power, 2015-09-11 15:07:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1339673002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1339673002/1

[commit-bot: I haz the power, 2015-09-11 15:10:00]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-11 15:10:10]

Patchset 1 (id:??) landed as
https://crrev.com/31026cd5a0e192b6b1f79f4b27bcbadca60c265e
Cr-Commit-Position: refs/heads/master@{#30698}