Fix overflow issue in Zone::New

Fix overflow issue in Zone::New

When requesting a large allocation near the end of the address space,
the computation could overflow and erroneously *not* grow the Zone
as required.

BUG=chromium:606115
LOG=y

Committed: https://crrev.com/3a9bfecfe41737aaf0dbf92ce68352f8acaaaf73
Cr-Commit-Position: refs/heads/master@{#35903}

[Jakob Kummerow, 2016-04-28 12:01:45]

jkummerow@chromium.org changed reviewers:
+ verwaest@chromium.org

[Toon Verwaest, 2016-04-29 08:50:16]

lgtm

[Jakob Kummerow, 2016-04-29 09:35:30]

The CQ bit was checked by jkummerow@chromium.org

[commit-bot: I haz the power, 2016-04-29 09:35:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1930873002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1930873002/1

[commit-bot: I haz the power, 2016-04-29 09:37:44]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-04-29 09:37:45]

Try jobs failed on following builders:
  v8_linux_rel_ng on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_rel_ng/builds/5054)

[Jakob Kummerow, 2016-04-29 10:03:23]

The CQ bit was checked by jkummerow@chromium.org

[Jakob Kummerow, 2016-04-29 10:03:23]

The patchset sent to the CQ was uploaded after l-g-t-m from
verwaest@chromium.org
Link to the patchset: https://codereview.chromium.org/1930873002/#ps20001
(title: "fix typo")

[commit-bot: I haz the power, 2016-04-29 10:03:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1930873002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1930873002/20001

[commit-bot: I haz the power, 2016-04-29 10:06:58]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-04-29 10:06:59]

Try jobs failed on following builders:
  v8_win_compile_dbg on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_win_compile_dbg/builds/1...)

[Jakob Kummerow, 2016-04-29 11:32:33]

The CQ bit was checked by jkummerow@chromium.org

[Jakob Kummerow, 2016-04-29 11:32:34]

The patchset sent to the CQ was uploaded after l-g-t-m from
verwaest@chromium.org
Link to the patchset: https://codereview.chromium.org/1930873002/#ps40001
(title: "windows likes casts")

[commit-bot: I haz the power, 2016-04-29 11:32:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1930873002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1930873002/40001

[commit-bot: I haz the power, 2016-04-29 11:54:04]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-05-01 22:03:42]

Description was changed from

==========
Fix overflow issue in Zone::New

When requesting a large allocation near the end of the address space,
the computation could overflow and erroneously *not* grow the Zone
as required.

BUG=chromium:606115
LOG=y
==========

to

==========
Fix overflow issue in Zone::New

When requesting a large allocation near the end of the address space,
the computation could overflow and erroneously *not* grow the Zone
as required.

BUG=chromium:606115
LOG=y

Committed: https://crrev.com/3a9bfecfe41737aaf0dbf92ce68352f8acaaaf73
Cr-Commit-Position: refs/heads/master@{#35903}
==========

[commit-bot: I haz the power, 2016-05-01 22:03:43]

Patchset 3 (id:??) landed as
https://crrev.com/3a9bfecfe41737aaf0dbf92ce68352f8acaaaf73
Cr-Commit-Position: refs/heads/master@{#35903}