Revert of [heap] Start sweeper tasks after evacuation.

Revert of [heap] Start sweeper tasks after evacuation. (patchset #2 id:20001 of https://chromiumcodereview.appspot.com/2428043002/ )

Reason for revert:
Performance regression on arm64: crbug.com/657776

Original issue's description:
> [heap] Start sweeper tasks after evacuation.
>
> This allows us to use more tasks for parallel evacuation.
>
> BUG=

TBR=mlippautz@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Committed: https://crrev.com/4490a7601c81647a4fb93da94360f271eb172473
Cr-Commit-Position: refs/heads/master@{#40465}

[ulan, 2016-10-20 12:14:45]

The CQ bit was checked by ulan@chromium.org

[ulan, 2016-10-20 12:14:46]

Created Revert of [heap] Start sweeper tasks after evacuation.

[commit-bot: I haz the power, 2016-10-20 12:14:54]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-20 12:15:05]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-11-17 22:07:55]

Description was changed from

==========
Revert of [heap] Start sweeper tasks after evacuation. (patchset #2 id:20001 of
https://chromiumcodereview.appspot.com/2428043002/ )

Reason for revert:
Performance regression on arm64: crbug.com/657776

Original issue's description:
> [heap] Start sweeper tasks after evacuation.
> 
> This allows us to use more tasks for parallel evacuation.
> 
> BUG=

TBR=mlippautz@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=
==========

to

==========
Revert of [heap] Start sweeper tasks after evacuation. (patchset #2 id:20001 of
https://chromiumcodereview.appspot.com/2428043002/ )

Reason for revert:
Performance regression on arm64: crbug.com/657776

Original issue's description:
> [heap] Start sweeper tasks after evacuation.
>
> This allows us to use more tasks for parallel evacuation.
>
> BUG=

TBR=mlippautz@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Committed: https://crrev.com/4490a7601c81647a4fb93da94360f271eb172473
Cr-Commit-Position: refs/heads/master@{#40465}
==========

[commit-bot: I haz the power, 2016-11-17 22:07:56]

Patchset 1 (id:??) landed as
https://crrev.com/4490a7601c81647a4fb93da94360f271eb172473
Cr-Commit-Position: refs/heads/master@{#40465}