Puts TLABs back into the build and fixes assert failure.

Puts TLABs back into the build and fixes assert failure.

This CL reintroduces the following commits (by reverting 91662ce57)

7568e1f18 : Reintroduces TLABs with fix for bug in 8b6fcf50e85d
91470e721 : Scavenger::UsedInWords() is now accurate to TLABs
479db734e : Fixes IO regression casued by 7568e1f18

R=asiva@google.com, rmacnak@google.com

Furthermore, this CL fixes a bug where unscheduling the mutator thread
and then walking the heap results in the assertion in
Scavenger::MakeNewSpaceIterable() fail due to a null heap.
Committed: https://github.com/dart-lang/sdk/commit/4c471b3f2733529d1b263596550b9bae3b38d88c

[rmacnak, 2017-08-09 20:54:22]

lgtm

[danunez, 2017-08-09 20:55:40]

Description was changed from

==========
Puts TLABs back into the build and fixes assert failure.

This CL reintroduces the following commits (by reverting 91662ce57)

7568e1f18 : Reintroduces TLABs with fix for bug in 8b6fcf50e85d
91470e721 : Scavenger::UsedInWords() is now accurate to TLABs
479db734e : Fixes IO regression casued by 7568e1f18

Furthermore, this CL fixes a bug where unscheduling the mutator thread
and then walking the heap results in the assertion in
Scavenger::MakeNewSpaceIterable() fail due to a null heap.

R=rmacnak@google.com,asiva@google.com
==========

to

==========
Puts TLABs back into the build and fixes assert failure.

This CL reintroduces the following commits (by reverting 91662ce57)

7568e1f18 : Reintroduces TLABs with fix for bug in 8b6fcf50e85d
91470e721 : Scavenger::UsedInWords() is now accurate to TLABs
479db734e : Fixes IO regression casued by 7568e1f18

R=asiva@google.com, rmacnak@google.com

Furthermore, this CL fixes a bug where unscheduling the mutator thread
and then walking the heap results in the assertion in
Scavenger::MakeNewSpaceIterable() fail due to a null heap.
Committed:
https://github.com/dart-lang/sdk/commit/4c471b3f2733529d1b263596550b9bae3b38d88c
==========

[danunez, 2017-08-09 20:55:42]

Committed patchset #1 (id:1) manually as
4c471b3f2733529d1b263596550b9bae3b38d88c (presubmit successful).