Add code age subtype tracking to --track-gc-object-stats

Add code age subtype tracking to --track-gc-object-stats

Adds counters which track the age of code in the heap during a gc if
--track-gc-object-stats is enabled.

 - Splits RecordObjectStats into RecordObjectStats, RecordCodeSubTypeStats and
   RecordFixedArraySubTypeStats.
 - Renames kNoAge to kNoAgeCodeAge to follow other code age enums and enable
   the name to be used in Macro based initialization of the counters.

BUG=None
R=hpayer@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=17369

[rmcilroy, 2013-10-11 19:00:19]

PTAL

[rmcilroy, 2013-10-16 10:50:41]

On 2013/10/11 19:00:19, rmcilroy wrote:
> PTAL

Ping?

[rmcilroy, 2013-10-22 09:24:33]

On 2013/10/16 10:50:41, rmcilroy wrote:
> On 2013/10/11 19:00:19, rmcilroy wrote:
> > PTAL
> 
> Ping?

Ping?

[Hannes Payer (out of office), 2013-10-22 10:41:43]

LGTM

[rmcilroy, 2013-10-22 11:37:10]

On 2013/10/22 10:41:43, Hannes Payer wrote:
> LGTM

Synced and rebased. Could you please land for me?

[Hannes Payer (out of office), 2013-10-24 10:50:57]

Committed patchset #3 manually as r17369 (presubmit successful).