X87: [stubs] Optimize LoadGlobalViaContextStub and StoreGlobalViaContextStub.

X87:  [stubs] Optimize LoadGlobalViaContextStub and StoreGlobalViaContextStub.

port d6ee366d5c5aef7c6bc550889a33520058b4e33a (r29834).

original commit message:

    This is the initial round of optimizations for the
    LoadGlobalViaContextStub and StoreGlobalViaContextStub, basically
    turning them into platform code stubs to avoid the Crankshaft overhead
    in the fast case, and making the runtime interface cheaper.

BUG=

Committed: https://crrev.com/4c6989914e1a2f92d009bd78a40febd318a2e5c2
Cr-Commit-Position: refs/heads/master@{#29839}

[chunyang.dai, 2015-07-24 09:29:01]

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

[chunyang.dai, 2015-07-24 09:29:01]

PTAL

[Weiliang, 2015-07-24 09:32:47]

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

[Weiliang, 2015-07-24 09:32:47]

lgtm

[commit-bot: I haz the power, 2015-07-24 09:32:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1258513003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1258513003/1

[commit-bot: I haz the power, 2015-07-24 10:08:50]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-24 10:09:02]

Patchset 1 (id:??) landed as
https://crrev.com/4c6989914e1a2f92d009bd78a40febd318a2e5c2
Cr-Commit-Position: refs/heads/master@{#29839}