Do not switch to two-byte string in String.fromCharCode if avoidable.

Do not switch to two-byte string in String.fromCharCode if avoidable.

R=bmeurer@chromium.org
BUG=v8:4536
LOG=N

Committed: https://crrev.com/742ae613eccbbfc8124c772af9a213f42df8875f
Cr-Commit-Position: refs/heads/master@{#31872}

[Yang, 2015-11-09 07:27:54]

The CQ bit was checked by yangguo@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-11-09 07:28:02]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1427743008/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1427743008/1

[commit-bot: I haz the power, 2015-11-09 07:47:29]

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

[commit-bot: I haz the power, 2015-11-09 07:47:29]

Dry run: This issue passed the CQ dry run.

[Benedikt Meurer, 2015-11-09 07:50:12]

https://codereview.chromium.org/1427743008/diff/1/src/js/string.js
File src/js/string.js (right):

https://codereview.chromium.org/1427743008/diff/1/src/js/string.js#newcode785
src/js/string.js:785: if (!%_IsSmi(code)) code = TO_NUMBER(code);
As discussed offline: Please do not do this %_IsSmi and explicit TO_NUMBER
gymnastics here. The & does an implicit ToNumber, which is even optimized by the
IC.

[Yang, 2015-11-09 07:53:08]

On 2015/11/09 07:50:12, Benedikt Meurer wrote:
> https://codereview.chromium.org/1427743008/diff/1/src/js/string.js
> File src/js/string.js (right):
> 
> https://codereview.chromium.org/1427743008/diff/1/src/js/string.js#newcode785
> src/js/string.js:785: if (!%_IsSmi(code)) code = TO_NUMBER(code);
> As discussed offline: Please do not do this %_IsSmi and explicit TO_NUMBER
> gymnastics here. The & does an implicit ToNumber, which is even optimized by
the
> IC.

uploaded new patch set.

[Benedikt Meurer, 2015-11-09 08:11:52]

LGTM with nit.

https://codereview.chromium.org/1427743008/diff/20001/src/js/string.js
File src/js/string.js (right):

https://codereview.chromium.org/1427743008/diff/20001/src/js/string.js#newcod...
src/js/string.js:794: if (!%_IsSmi(code)) code = TO_NUMBER(code) & 0xffff;
Nit: Please also fix this one.

[Yang, 2015-11-09 08:17:15]

The CQ bit was checked by yangguo@chromium.org

[Yang, 2015-11-09 08:17:16]

The patchset sent to the CQ was uploaded after l-g-t-m from bmeurer@chromium.org
Link to the patchset: https://codereview.chromium.org/1427743008/#ps60001
(title: "also fix fast path")

[commit-bot: I haz the power, 2015-11-09 08:17:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1427743008/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1427743008/60001

[commit-bot: I haz the power, 2015-11-09 08:53:34]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-11-09 08:53:52]

Patchset 4 (id:??) landed as
https://crrev.com/742ae613eccbbfc8124c772af9a213f42df8875f
Cr-Commit-Position: refs/heads/master@{#31872}