PPC: Add unoptimized/optimized variants of MathFloor TF code stub

PPC: Add unoptimized/optimized variants of MathFloor TF code stub

Port 8f13b655b8a10dae2116dd18b32f09337bb2d410

Original commit message:
    - Add a TurboFanIC class, derived from TurboFanCodeStub, that
      automatically distinguishes between versions of the IC called from
      optimized and unoptimized code.
    - Add appropriate InterfaceDescriptors for both the versions of the
      stub called from unoptimized and optimized code
    - Change the MathFloor TF stub generator to output either the
      for-optimized or for-unoptimized version based on the minor_key
      parameter.

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

Committed: https://crrev.com/0640e295770c4831cd79b197e26e78a1eb3840b3
Cr-Commit-Position: refs/heads/master@{#29542}

[dstence, 2015-07-08 18:44:59]

lgtm

[MTBrandyberry, 2015-07-08 18:46:00]

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

[commit-bot: I haz the power, 2015-07-08 18:46:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1207253003/1

[commit-bot: I haz the power, 2015-07-08 19:11:35]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-08 19:11:46]

Patchset 1 (id:??) landed as
https://crrev.com/0640e295770c4831cd79b197e26e78a1eb3840b3
Cr-Commit-Position: refs/heads/master@{#29542}