Use conservative hash table capacity growth during entire snapshotting.

Use conservative hash table capacity growth during entire snapshotting.

We want to use the conservative growth strategy during
- isolate initialization
- bootstrapping a context

But not when
- not creating a snapshot
- running additional code for custom snapshot.

R=mvstanton@chromium.org

Committed: https://crrev.com/4f4c90d0bbbb78e054ee5451455df12c5ff9a29f
Cr-Commit-Position: refs/heads/master@{#28586}

[mvstanton, 2015-05-22 11:01:46]

lgtm

[Yang, 2015-05-22 11:20:02]

The CQ bit was checked by yangguo@chromium.org

[commit-bot: I haz the power, 2015-05-22 11:20:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1155823003/1

[commit-bot: I haz the power, 2015-05-22 11:50:42]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-22 11:50:58]

Patchset 1 (id:??) landed as
https://crrev.com/4f4c90d0bbbb78e054ee5451455df12c5ff9a29f
Cr-Commit-Position: refs/heads/master@{#28586}