X87: [turbofan] Avoid unnecessary write barriers and improve code generation.

X87: [turbofan] Avoid unnecessary write barriers and improve code generation.

   port 1e2770123bd5c1cf7631bf11be846f0fbd884c08 (r31914)

   original commit message:
   Avoid write barriers when storing values in the root set, and use
   cheaper write barriers for storing maps or tagged pointers. Also
   improve the generated code for write barriers, utilizing the out
   of line code mechanism that is available to TurboFan backends,
   which moves the unlikely case out of the hot path.

BUG=

Committed: https://crrev.com/f1478bd141429a74b29029781de5784a5d561d33
Cr-Commit-Position: refs/heads/master@{#31935}

[zhengxing.li, 2015-11-11 02:40:32]

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

[Weiliang, 2015-11-11 03:17:17]

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

[Weiliang, 2015-11-11 03:17:18]

lgtm

[commit-bot: I haz the power, 2015-11-11 03:17:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1435743003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1435743003/1

[commit-bot: I haz the power, 2015-11-11 03:37:45]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-11 03:38:05]

Patchset 1 (id:??) landed as
https://crrev.com/f1478bd141429a74b29029781de5784a5d561d33
Cr-Commit-Position: refs/heads/master@{#31935}