Remove GC metadata of code object before serializing.

Remove GC metadata of code object before serializing.

Follow up on discussion of https://codereview.chromium.org/1310503006/

BUG=
LOG=N

Committed: https://crrev.com/b370f6d8230bb75722eed57e5f72ec6db1ce4177
Cr-Commit-Position: refs/heads/master@{#30562}

[oth, 2015-09-03 12:50:05]

oth@chromium.org changed reviewers:
+ rmcilroy@chromium.org, ulan@chromium.org

[oth, 2015-09-03 12:50:05]

rmcilroy@chromium.org, ulan@chromium.org: PTAL

Thanks

[rmcilroy, 2015-09-03 12:51:50]

lgtm, thanks!

[ulan_google, 2015-09-03 12:52:33]

ulan@google.com changed reviewers:
+ ulan@google.com

[ulan_google, 2015-09-03 12:52:34]

lgtm

[oth, 2015-09-03 12:55:35]

The CQ bit was checked by oth@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-03 12:55:41]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1313953008/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1313953008/1

[commit-bot: I haz the power, 2015-09-03 13:20:26]

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

[commit-bot: I haz the power, 2015-09-03 13:20:26]

Dry run: This issue passed the CQ dry run.

[oth, 2015-09-03 13:25:27]

The CQ bit was checked by oth@chromium.org

[commit-bot: I haz the power, 2015-09-03 13:25:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1313953008/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1313953008/1

[oth, 2015-09-03 13:26:21]

thanks all!

[commit-bot: I haz the power, 2015-09-03 13:48:04]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-03 13:48:20]

Patchset 1 (id:??) landed as
https://crrev.com/b370f6d8230bb75722eed57e5f72ec6db1ce4177
Cr-Commit-Position: refs/heads/master@{#30562}