Revert of Cleanup: Remove unneeded SSE2 checks and unused code.

Revert of Cleanup: Remove unneeded SSE2 checks and unused code. (patchset #4 of https://codereview.chromium.org/459603003/)

Reason for revert:
Passed the win x64 trybot, but failed on the win 64 builder.

Original issue's description:
> Cleanup: Remove unneeded SSE2 checks and unused code.
> 
> BUG=349320
> 
> Committed: https://chromium.googlesource.com/chromium/src/+/b2cd99b39c3744f61231f8818f6c7a3d2881f0f0

TBR=cpu@chromium.org,dalecurtis@chromium.org,senorblanco@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=349320
Committed: https://crrev.com/55234498566db7ff749af32df42eafce48d2837c
Cr-Commit-Position: refs/heads/master@{#292101}

[Lei Zhang, 2014-08-27 06:32:55]

Created Revert of Cleanup: Remove unneeded SSE2 checks and unused code.

[commit-bot: I haz the power, 2014-08-27 06:33:30]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/thestig@chromium.org/513663002/1

[commit-bot: I haz the power, 2014-08-27 06:34:26]

Committed patchset #1 (1) as 1b838f36c595a273c66156230637681cdc85e57e

[commit-bot: I haz the power, 2014-09-10 02:49:51]

Patchset 1 (id:??) landed as
https://crrev.com/55234498566db7ff749af32df42eafce48d2837c
Cr-Commit-Position: refs/heads/master@{#292101}