PPC: [compiler] Introduce code stubs for string relational comparisons.

PPC: [compiler] Introduce code stubs for string relational comparisons.

Port 5912e0f014bd7b7d52cdc293145a912a4ecf2cf3

Original commit message:
    Add StringLessThanStub, StringLessThanOrEqualStub, StringGreaterThanStub
    and StringGreaterThanOrEqualStub, based on the CodeStubAssembler, and
    hook them up with TurboFan (and Ignition). The stubs are currently
    essentially comparable with the StringCompareStub, which is now
    obsolete. We can later extend these stubs to cover more interesting
    cases (i.e. two byte sequential string comparisons, etc.).

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=

Committed: https://crrev.com/35bce027d20287bc44c56112b1fbeac0b31c4a5c
Cr-Commit-Position: refs/heads/master@{#34508}

[MTBrandyberry, 2016-03-04 17:17:35]

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

[commit-bot: I haz the power, 2016-03-04 17:17:48]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1761403002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1761403002/1

[commit-bot: I haz the power, 2016-03-04 17:41:10]

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

[commit-bot: I haz the power, 2016-03-04 17:41:11]

Dry run: This issue passed the CQ dry run.

[john.yan, 2016-03-04 20:01:47]

lgtm

[MTBrandyberry, 2016-03-04 20:02:54]

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

[commit-bot: I haz the power, 2016-03-04 20:02:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1761403002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1761403002/1

[commit-bot: I haz the power, 2016-03-04 20:05:00]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-03-04 20:05:55]

Description was changed from

==========
PPC: [compiler] Introduce code stubs for string relational comparisons.

Port 5912e0f014bd7b7d52cdc293145a912a4ecf2cf3

Original commit message:
    Add StringLessThanStub, StringLessThanOrEqualStub, StringGreaterThanStub
    and StringGreaterThanOrEqualStub, based on the CodeStubAssembler, and
    hook them up with TurboFan (and Ignition). The stubs are currently
    essentially comparable with the StringCompareStub, which is now
    obsolete. We can later extend these stubs to cover more interesting
    cases (i.e. two byte sequential string comparisons, etc.).

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com,
michael_dawson@ca.ibm.com
BUG=
==========

to

==========
PPC: [compiler] Introduce code stubs for string relational comparisons.

Port 5912e0f014bd7b7d52cdc293145a912a4ecf2cf3

Original commit message:
    Add StringLessThanStub, StringLessThanOrEqualStub, StringGreaterThanStub
    and StringGreaterThanOrEqualStub, based on the CodeStubAssembler, and
    hook them up with TurboFan (and Ignition). The stubs are currently
    essentially comparable with the StringCompareStub, which is now
    obsolete. We can later extend these stubs to cover more interesting
    cases (i.e. two byte sequential string comparisons, etc.).

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com,
michael_dawson@ca.ibm.com
BUG=

Committed: https://crrev.com/35bce027d20287bc44c56112b1fbeac0b31c4a5c
Cr-Commit-Position: refs/heads/master@{#34508}
==========

[commit-bot: I haz the power, 2016-03-04 20:05:56]

Patchset 1 (id:??) landed as
https://crrev.com/35bce027d20287bc44c56112b1fbeac0b31c4a5c
Cr-Commit-Position: refs/heads/master@{#34508}