Fix clobbered register when setting this_function variable.

Fix clobbered register when setting this_function variable.

Reland of https://crrev.com/bf2bbc8ba508ccd21edf3c08d2e4192c4764ae91

R=bmeurer@chromium.org
TEST=mjsunit/regress/regress-crbug-498022
BUG=chromium:498022
LOG=N

Committed: https://crrev.com/a7697bdcc761f2841df1a8251c5f65696f0e790c
Cr-Commit-Position: refs/heads/master@{#29372}

[Michael Starzinger, 2015-06-30 09:57:34]

Note that this is a reland, patch set #1 is the original CL and patch set #2
contains the fixup.

Benedikt: PTAL.
Arv: FYI.

[Benedikt Meurer, 2015-06-30 10:37:14]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2015-06-30 10:37:14]

lgtm

[commit-bot: I haz the power, 2015-06-30 10:37:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1214483008/20001

[commit-bot: I haz the power, 2015-06-30 10:39:06]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-06-30 10:39:24]

Patchset 2 (id:??) landed as
https://crrev.com/a7697bdcc761f2841df1a8251c5f65696f0e790c
Cr-Commit-Position: refs/heads/master@{#29372}

[arv (Not doing code reviews), 2015-06-30 14:18:27]

arv@chromium.org changed reviewers:
+ arv@chromium.org

[arv (Not doing code reviews), 2015-06-30 14:18:27]

LGTM