X87: [runtime] Add %ToString and %_ToString and remove the TO_STRING builtin.

X87: [runtime] Add %ToString and %_ToString and remove the TO_STRING builtin.

port 09de997b3504368d40644afa7310b90faff5d09c (r30442).

original commit message:

    This adds a new ToString runtime function and a fast-path ToStringStub
    (which is just a simple dispatcher for existing functionality), and also
    implements %_ToName using the ToStringStub.

R=weiliang.lin@intel.com
BUG=

Committed: https://crrev.com/3f6e5b3014685c90610da107193400af7f7790d4
Cr-Commit-Position: refs/heads/master@{#30460}

[chunyang.dai, 2015-08-31 07:30:47]

PTAL

[Weiliang, 2015-08-31 08:57:54]

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

[Weiliang, 2015-08-31 08:57:55]

lgtm

[commit-bot: I haz the power, 2015-08-31 08:58:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1326473002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1326473002/1

[commit-bot: I haz the power, 2015-08-31 09:23:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-31 09:23:47]

Patchset 1 (id:??) landed as
https://crrev.com/3f6e5b3014685c90610da107193400af7f7790d4
Cr-Commit-Position: refs/heads/master@{#30460}