Revert of [heap] Do not invoke GC to make heap iterable.

Revert of [heap] Do not invoke GC to make heap iterable. (patchset #5 id:80001 of https://codereview.chromium.org/1961373003/ )

Reason for revert:
Breaks https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20gc%20stress/builds/3551

Original issue's description:
> [heap] Do not invoke GC to make heap iterable.
>
> Remove kMakeHeapIterableMask since the heap is always iterable.
>
> BUG=chromium:580959
> LOG=n
>
> Committed: https://crrev.com/7c1cac4888a248fda3fa6de3624f32a6babb37e9
> Cr-Commit-Position: refs/heads/master@{#36333}

TBR=ulan@chromium.org,yangguo@chromium.org,hpayer@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:580959
Committed: https://crrev.com/0aa3707dc403a5285d216b01d24faa27375ceec4
Cr-Commit-Position: refs/heads/master@{#36335}

[Michael Achenbach, 2016-05-18 19:21:45]

Created Revert of [heap] Do not invoke GC to make heap iterable.

[commit-bot: I haz the power, 2016-05-18 19:21:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1987363002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1987363002/1

[commit-bot: I haz the power, 2016-05-18 19:22:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-05-18 19:23:15]

Description was changed from

==========
Revert of [heap] Do not invoke GC to make heap iterable. (patchset #5 id:80001
of https://codereview.chromium.org/1961373003/ )

Reason for revert:
Breaks
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20gc%20stress/...

Original issue's description:
> [heap] Do not invoke GC to make heap iterable.
> 
> Remove kMakeHeapIterableMask since the heap is always iterable.
> 
> BUG=chromium:580959
> LOG=n
> 
> Committed: https://crrev.com/7c1cac4888a248fda3fa6de3624f32a6babb37e9
> Cr-Commit-Position: refs/heads/master@{#36333}

TBR=ulan@chromium.org,yangguo@chromium.org,hpayer@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:580959
==========

to

==========
Revert of [heap] Do not invoke GC to make heap iterable. (patchset #5 id:80001
of https://codereview.chromium.org/1961373003/ )

Reason for revert:
Breaks
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20gc%20stress/...

Original issue's description:
> [heap] Do not invoke GC to make heap iterable.
>
> Remove kMakeHeapIterableMask since the heap is always iterable.
>
> BUG=chromium:580959
> LOG=n
>
> Committed: https://crrev.com/7c1cac4888a248fda3fa6de3624f32a6babb37e9
> Cr-Commit-Position: refs/heads/master@{#36333}

TBR=ulan@chromium.org,yangguo@chromium.org,hpayer@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:580959

Committed: https://crrev.com/0aa3707dc403a5285d216b01d24faa27375ceec4
Cr-Commit-Position: refs/heads/master@{#36335}
==========

[commit-bot: I haz the power, 2016-05-18 19:23:17]

Patchset 1 (id:??) landed as
https://crrev.com/0aa3707dc403a5285d216b01d24faa27375ceec4
Cr-Commit-Position: refs/heads/master@{#36335}