Serialzier: expand string table as last step before deserializing.

Serialzier: expand string table as last step before deserializing.

Not doing so could result in this scenario:
- We ensure that the string table is large enough. It is.
- We compile code stubs, which triggers a GC.
- The GC clears string table entries.
- This increases the number of deleted entries in the table.
- When the deserializer hooks up internalized strings into the
  table, we ensure that the table is large enough every time.
- Due to changed number of deleted entries, the heuristic
  decides to expand the string table.
- Allocation during deserialization causes assertion to fail.

BUG=chromium:502085
LOG=N

Committed: https://crrev.com/37928334a1129c07c83d17e7a1421f3a3d8e8571
Cr-Commit-Position: refs/heads/master@{#29134}

[Yang, 2015-06-19 07:13:13]

yangguo@chromium.org changed reviewers:
+ jochen@chromium.org

[jochen (gone - plz use gerrit), 2015-06-19 07:15:24]

lgtm

[Yang, 2015-06-19 07:18:21]

The CQ bit was checked by yangguo@chromium.org

[commit-bot: I haz the power, 2015-06-19 07:18:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1197633002/1

[commit-bot: I haz the power, 2015-06-19 08:07:09]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-19 08:07:17]

Patchset 1 (id:??) landed as
https://crrev.com/37928334a1129c07c83d17e7a1421f3a3d8e8571
Cr-Commit-Position: refs/heads/master@{#29134}