Revert of Revert of Update V8 to version 4.3.15.

Revert of Revert of Update V8 to version 4.3.15. (patchset #1 id:1 of https://codereview.chromium.org/975713002/)

Reason for revert:
The roll wasn't the cause for issue 463436. Therefore relanding.

Original issue's description:
> 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}

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

Committed: https://crrev.com/8e40655abfe830b43e4820feb903fc72bf049a59
Cr-Commit-Position: refs/heads/master@{#319023}

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

Created Revert of Revert of Update V8 to version 4.3.15.

[commit-bot: I haz the power, 2015-03-04 07:10:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/977583004/1

[commit-bot: I haz the power, 2015-03-04 07:11:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-04 07:11:58]

Patchset 1 (id:??) landed as
https://crrev.com/8e40655abfe830b43e4820feb903fc72bf049a59
Cr-Commit-Position: refs/heads/master@{#319023}