Don't allocate AstTyper with the zone allocator.

Don't allocate AstTyper with the zone allocator.

While the class Type objects the AstTyper generates should be
allocated to zone memory, there's no particular reason
the typer object itself needs to be.

BUG=None
TEST=None
R=rossberg@chromium.org,titzer@chromium.org
LOG=N

Committed: https://crrev.com/233599fa70818f1ef6ff2860f7762ab29f32653f
Cr-Commit-Position: refs/heads/master@{#30313}

[rossberg, 2015-08-21 09:40:22]

lgtm

[titzer, 2015-08-21 10:27:18]

On 2015/08/21 09:40:22, rossberg wrote:
> lgtm

lgtm as well

[bradn, 2015-08-21 18:13:57]

The CQ bit was checked by bradnelson@google.com

[commit-bot: I haz the power, 2015-08-21 18:14:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1303843003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1303843003/20001

[commit-bot: I haz the power, 2015-08-21 18:15:38]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-21 18:15:50]

Patchset 2 (id:??) landed as
https://crrev.com/233599fa70818f1ef6ff2860f7762ab29f32653f
Cr-Commit-Position: refs/heads/master@{#30313}