Revert of Revert "Remove early bail-out in VisitWeakList to investigate chrasher."

Revert of Revert "Remove early bail-out in VisitWeakList to investigate chrasher." (patchset #1 id:1 of https://codereview.chromium.org/1080303002/)

Reason for revert:
Still doesn't work

Original issue's description:
> Revert "Remove early bail-out in VisitWeakList to investigate chrasher."
>
> >  BUG=468601
> >  LOG=n
> >
> >  Review URL: https://codereview.chromium.org/1016353002
> >
> >  Cr-Commit-Position: refs/heads/master@{#27317}
>
> R=hpayer@chromium.org
> BUG=v8:3996, chromium:468601
> LOG=n
>
> Committed: https://crrev.com/835eeafe32f442d7b43fe175237de2c70ed7ceef
> Cr-Commit-Position: refs/heads/master@{#27814}

TBR=hpayer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:3996, chromium:468601
Committed: https://crrev.com/fd7d881e2be920cb1c020a5663bad400833770ee
Cr-Commit-Position: refs/heads/master@{#27902}

[jochen (gone - plz use gerrit), 2015-04-16 20:59:45]

Created Revert of Revert "Remove early bail-out in VisitWeakList to investigate
chrasher."

[commit-bot: I haz the power, 2015-04-16 21:00:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1092783002/1

[commit-bot: I haz the power, 2015-04-16 21:00:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-16 21:00:29]

Patchset 1 (id:??) landed as
https://crrev.com/fd7d881e2be920cb1c020a5663bad400833770ee
Cr-Commit-Position: refs/heads/master@{#27902}