X87: [runtime] Implement %_ToLength via ToLengthStub.

X87: [runtime] Implement %_ToLength via ToLengthStub.

    port e678a0f9a961165ab43cd1a6080fcb11995b701a (r31358)

    original commit message:
    Use %_ToLength for TO_LENGTH, implemented via a ToLengthStub
    that supports a fast path for small integers. Everything else is still
    handled in the runtime.

BUG=

Committed: https://crrev.com/9f4ff3b1cd2008c90383776a64efa3de63908d95
Cr-Commit-Position: refs/heads/master@{#31542}

[zhengxing.li, 2015-10-23 14:58:38]

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

[Weiliang, 2015-10-26 03:27:34]

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

[Weiliang, 2015-10-26 03:27:35]

lgtm

[commit-bot: I haz the power, 2015-10-26 03:27:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1421803002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1421803002/1

[commit-bot: I haz the power, 2015-10-26 03:50:32]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-26 03:51:06]

Patchset 1 (id:??) landed as
https://crrev.com/9f4ff3b1cd2008c90383776a64efa3de63908d95
Cr-Commit-Position: refs/heads/master@{#31542}