X87: [stubs] Refactor StringCompareStub and use it for HStringCompareAndBranch.

X87: [stubs] Refactor StringCompareStub and use it for HStringCompareAndBranch.

port 8016547c8e6fde00fff0a1791f3c83b444d8af25 (r30818).

original commit message:

    The StringCompareStub used to take its parameters on the (JavaScript)
    stack, which made it impossible to use in TurboFan. Actually
    StringCompareStub was currently completely unused. This changes the
    calling convention to something TurboFan compatible and introduces a
    CallInterfaceDescriptor for StringCompareStub. It also changes
    HStringCompareAndBranch to use the StringCompareStub instead of using
    the full blown CompareICStub for a stupid string comparison.

BUG=

Committed: https://crrev.com/be04dd5c9e6023cc4114bd41f80fde3201e784e9
Cr-Commit-Position: refs/heads/master@{#30845}

[chunyang.dai, 2015-09-21 02:25:39]

chunyang.dai@intel.com changed reviewers:
+ weiliang.lin@intel.com

[chunyang.dai, 2015-09-21 02:25:39]

PTAL

[Weiliang, 2015-09-21 08:50:34]

The CQ bit was checked by weiliang.lin@intel.com

[Weiliang, 2015-09-21 08:50:35]

lgtm

[commit-bot: I haz the power, 2015-09-21 08:50:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1355983003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1355983003/1

[commit-bot: I haz the power, 2015-09-21 09:18:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-21 09:18:27]

Patchset 1 (id:??) landed as
https://crrev.com/be04dd5c9e6023cc4114bd41f80fde3201e784e9
Cr-Commit-Position: refs/heads/master@{#30845}