Debugger: ensure that functions with debug info have code with break slots.

Debugger: ensure that functions with debug info have code with break slots.

This helps reasoning about setting break points. Functions that
have debug info is also guaranteed to be able to set break points.

R=ulan@chromium.org
BUG=v8:4132
LOG=N

Committed: https://crrev.com/83207b93f4d23e1df5c4f9bae1a97c8205b079e5
Cr-Commit-Position: refs/heads/master@{#29698}

[ulan, 2015-07-15 10:48:06]

lgtm

[Yang, 2015-07-16 09:08:35]

The CQ bit was checked by yangguo@chromium.org

[commit-bot: I haz the power, 2015-07-16 09:08:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1227213003/1

[commit-bot: I haz the power, 2015-07-16 09:38:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-16 09:38:37]

Patchset 1 (id:??) landed as
https://crrev.com/83207b93f4d23e1df5c4f9bae1a97c8205b079e5
Cr-Commit-Position: refs/heads/master@{#29698}