Fixed Hydrogen environment handling for mul-i on ARM and ARM64.

Fixed Hydrogen environment handling for mul-i on ARM and ARM64.

The whole logic in DoMul makes me cry, so I made only the minimal
change to fix the issue...

BUG=v8:451322
LOG=y

Committed: https://crrev.com/a7d67a64f11100434b196143e2ba516f8c13697a
Cr-Commit-Position: refs/heads/master@{#26261}

[Sven Panne, 2015-01-23 13:59:10]

svenpanne@chromium.org changed reviewers:
+ bmeurer@chromium.org

[Benedikt Meurer, 2015-01-23 14:08:42]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2015-01-23 14:08:42]

URGS ^W LGTM

[commit-bot: I haz the power, 2015-01-23 14:09:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/873703002/1

[commit-bot: I haz the power, 2015-01-23 14:30:28]

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

[commit-bot: I haz the power, 2015-01-23 14:30:29]

Try jobs failed on following builders:
  v8_linux_arm64_rel on tryserver.v8
(http://build.chromium.org/p/tryserver.v8/builders/v8_linux_arm64_rel/builds/2314)

[Sven Panne, 2015-01-26 08:05:22]

The CQ bit was checked by svenpanne@chromium.org

[commit-bot: I haz the power, 2015-01-26 08:06:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/873703002/20001

[commit-bot: I haz the power, 2015-01-26 08:35:55]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-26 08:36:10]

Patchset 2 (id:??) landed as
https://crrev.com/a7d67a64f11100434b196143e2ba516f8c13697a
Cr-Commit-Position: refs/heads/master@{#26261}