Turn off overapproximation of the weak closure again

Turn off overapproximation of the weak closure again

As long as we still have to process global handles, the impact is not
yet worthwhile

BUG=v8:3862
R=hpayer@chromium.org
LOG=y

Committed: https://crrev.com/294cdc6aecbd7f76be68217da4b3d35901ebce4b
Cr-Commit-Position: refs/heads/master@{#27570}

[Hannes Payer (out of office), 2015-04-01 08:38:42]

ok, lgtm

[Hannes Payer (out of office), 2015-04-01 16:18:04]

The CQ bit was checked by hpayer@chromium.org

[commit-bot: I haz the power, 2015-04-01 16:18:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1050443002/1

[commit-bot: I haz the power, 2015-04-01 16:52:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-01 16:52:40]

Patchset 1 (id:??) landed as
https://crrev.com/294cdc6aecbd7f76be68217da4b3d35901ebce4b
Cr-Commit-Position: refs/heads/master@{#27570}

[jochen (gone - plz use gerrit), 2015-04-07 09:45:19]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1068723003/ by jochen@chromium.org.

The reason for reverting is: this indeed drops the max major gc time
considerable, so turn it back on.