Serializer forces flushing of optimized code map.

Serializer forces flushing of optimized code map.

This makes sure that the GC fully flushes the optimized code map when
the serializer is preparing a snapshot. Otherwise closures and contexts
could end up in the startup snapshot.

R=hpayer@chromium.org
TEST=cctest/test-serialize/SerializeInternalReference

Committed: https://crrev.com/84f0a33ce0020f16514b8c01ff2bbe8b027e027e
Cr-Commit-Position: refs/heads/master@{#29461}

[Michael Starzinger, 2015-07-01 16:21:43]

Hannes: PTAL.
Yang: FYI.

[Hannes Payer (out of office), 2015-07-02 18:26:28]

lgtm

[Michael Starzinger, 2015-07-03 07:45:57]

The CQ bit was checked by mstarzinger@chromium.org

[commit-bot: I haz the power, 2015-07-03 07:46:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1215063007/1

[commit-bot: I haz the power, 2015-07-03 07:47:32]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-03 07:47:56]

Patchset 1 (id:??) landed as
https://crrev.com/84f0a33ce0020f16514b8c01ff2bbe8b027e027e
Cr-Commit-Position: refs/heads/master@{#29461}