Serializer: reorder root list items.

Serializer: reorder root list items.

The first 32 root list items can be encoded very efficiently.
By reordering, we can better encode some often referenced root objects.

R=mvstanton@chromium.org

Committed: https://crrev.com/4ddeac6cd7ec6e0242fd8314a02e62e5e74ff457
Cr-Commit-Position: refs/heads/master@{#27293}

[mvstanton, 2015-03-19 09:11:02]

lgtm

[Yang, 2015-03-19 09:11:09]

The CQ bit was checked by yangguo@chromium.org

[commit-bot: I haz the power, 2015-03-19 09:11:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1019243002/1

[commit-bot: I haz the power, 2015-03-19 09:33:53]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-19 09:34:11]

Patchset 1 (id:??) landed as
https://crrev.com/4ddeac6cd7ec6e0242fd8314a02e62e5e74ff457
Cr-Commit-Position: refs/heads/master@{#27293}

[Erik Corry, 2015-03-19 12:14:06]

erik.corry@gmail.com changed reviewers:
+ erik.corry@gmail.com

[Erik Corry, 2015-03-19 12:14:06]

https://codereview.chromium.org/1019243002/diff/1/src/heap/heap.h
File src/heap/heap.h (right):

https://codereview.chromium.org/1019243002/diff/1/src/heap/heap.h#newcode57
src/heap/heap.h:57: V(Map, cons_one_byte_string_map, ConsOneByteStringMap)      
                \
If these are frequent in the snapshot perhaps we should be flattening strings
before generating the snapshot.