Ensure Zone returns correctly aligned pointers for allocations with

Ensure Zone returns correctly aligned pointers for allocations with
sizes that are a multiple of 8 bytes on 32-bit platforms.

On 32-bit platforms, Zone is meant to return 8-byte aligned pointers for
allocations with sizes that are a multiple of 8 bytes. However, this was
not guaranteed for allocations that required the size of the Zone to be
expanded. In this case, Zone could sometimes return pointers with 4-byte
alignment.

BUG=v8:5668

[Chris Coulson, 2017-01-06 17:20:53]

Description was changed from

==========
Ensure Zone returns correctly aligned pointers for allocations with
sizes that are a multiple of 8 bytes on 32-bit platforms.

On 32-bit platforms, Zone is meant to return 8-byte aligned pointers for
allocations with sizes that are a multiple of 8 bytes. However, this was
not guaranteed for allocations that required the size of the Zone to be
expanded. In this case, Zone could sometimes return pointers with 4-byte
alignment.

BUG=5668
==========

to

==========
Ensure Zone returns correctly aligned pointers for allocations with
sizes that are a multiple of 8 bytes on 32-bit platforms.

On 32-bit platforms, Zone is meant to return 8-byte aligned pointers for
allocations with sizes that are a multiple of 8 bytes. However, this was
not guaranteed for allocations that required the size of the Zone to be
expanded. In this case, Zone could sometimes return pointers with 4-byte
alignment.

BUG=v8:5668
==========

[jochen (gone - plz use gerrit), 2017-01-31 15:07:43]

jochen@chromium.org changed reviewers:
+ jochen@chromium.org, verwaest@chromium.org

[jochen (gone - plz use gerrit), 2017-01-31 15:07:44]

instead of adding this runtime correction of the alignment, why not just change
kAlignment on those architectures?

could you add a unit test?

[jochen (gone - plz use gerrit), 2017-01-31 15:15:03]

btw, your account appears to not be part of the CCLA from Canonical. Can you
please work internally with whoever manages the license agreement to get
yourself added, so we can accept contributions?

Once that's done, you should also add yourself to AUTHORS