Revert of Update V8 to version 4.3.15.

Revert of Update V8 to version 4.3.15. (patchset #1 id:1 of https://codereview.chromium.org/969053002/)

Reason for revert:
Speculative revert for issue 463436.

Original issue's description:
> Update V8 to version 4.3.15.
>
> Summary of changes available at:
> https://chromium.googlesource.com/v8/v8/+log/c791d841..155278d6
>
> Please follow these instructions for assigning/CC'ing issues:
> https://code.google.com/p/v8-wiki/wiki/TriagingIssues
>
> TBR=machenbach@chromium.org
>
> Committed: https://crrev.com/32e6c72188d6b0b948d668afdc1cb209d44c2e70
> Cr-Commit-Position: refs/heads/master@{#318755}

TBR=v8-autoroll@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Committed: https://crrev.com/0607e55050323137b334f8569a7e522d6f1844da
Cr-Commit-Position: refs/heads/master@{#318880}

[Michael Achenbach, 2015-03-03 15:57:17]

Created Revert of Update V8 to version 4.3.15.

[commit-bot: I haz the power, 2015-03-03 15:59:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/975713002/1

[commit-bot: I haz the power, 2015-03-03 16:00:31]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-03 16:01:19]

Patchset 1 (id:??) landed as
https://crrev.com/0607e55050323137b334f8569a7e522d6f1844da
Cr-Commit-Position: refs/heads/master@{#318880}

[Michael Achenbach, 2015-03-04 07:09:47]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/977583004/ by machenbach@chromium.org.

The reason for reverting is: The roll wasn't the cause for issue 463436.
Therefore relanding..