Revert of X87: disable the regress-undefined-nan test case for x87.

Revert of X87: disable the regress-undefined-nan test case for x87. (patchset #1 id:1 of https://codereview.chromium.org/1414733004/ )

Reason for revert:
because of merge mistake, "regress/" is missed when skipping one test case for X87.

 "regress/" will be added when relanding it.

Original issue's description:
> X87: disable the regress-undefined-nan test case for x87.
>
>   The reason is when native_context_specialization flag is ture, X87 turbofan
>   will hit the known issue that X87 will change a sNaN to qNaN by default. And
>   then it will fail when bit-comparing the source (sNaN) and the result (qNaN).
>
> BUG=
>
> Committed: https://crrev.com/b3c719ebbad6c87afefa33a7d0b3f412b2e304db
> Cr-Commit-Position: refs/heads/master@{#31530}

TBR=bmeurer@chromium.org,weiliang.lin@intel.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Committed: https://crrev.com/e8ff5181d3fb9da9f8460d969c0130535f86c7b4
Cr-Commit-Position: refs/heads/master@{#31543}

[chunyang.dai, 2015-10-26 03:43:50]

Created Revert of X87: disable the regress-undefined-nan test case for x87.

[commit-bot: I haz the power, 2015-10-26 03:43:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1417303005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1417303005/1

[commit-bot: I haz the power, 2015-10-26 03:43:56]

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

[commit-bot: I haz the power, 2015-10-26 03:43:57]

No L-G-T-M from a valid reviewer yet. Only full committers are accepted.
Even if an L-G-T-M may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Benedikt Meurer, 2015-10-26 04:42:10]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2015-10-26 04:42:11]

lgtm

[commit-bot: I haz the power, 2015-10-26 04:42:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1417303005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1417303005/1

[commit-bot: I haz the power, 2015-10-26 04:42:33]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-26 04:42:44]

Patchset 1 (id:??) landed as
https://crrev.com/e8ff5181d3fb9da9f8460d969c0130535f86c7b4
Cr-Commit-Position: refs/heads/master@{#31543}