Refactor BreakLocationIterator.

Refactor BreakLocationIterator.

We now have BreakLocation::Iterator to iterate via RelocIterator, and
create a BreakLocation when we are done iterating. The reloc info is
stored in BreakLocation in a GC-safe way and instantiated on demand.

R=ulan@chromium.org
BUG=v8:3924
LOG=N

Committed: https://crrev.com/1a608493e55eacf5c7569e2b1213da42eb0e6207
Cr-Commit-Position: refs/heads/master@{#26983}

[ulan, 2015-03-03 10:22:16]

lgtm

[Yang, 2015-03-03 10:23:44]

The CQ bit was checked by yangguo@chromium.org

[commit-bot: I haz the power, 2015-03-03 10:24:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/967323002/1

[commit-bot: I haz the power, 2015-03-03 10:28:12]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-03 10:28:13]

Try jobs failed on following builders:
  v8_linux64_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_rel/builds/3474)

[Yang, 2015-03-04 12:44:23]

The CQ bit was checked by yangguo@chromium.org

[Yang, 2015-03-04 12:44:24]

The patchset sent to the CQ was uploaded after l-g-t-m from ulan@chromium.org
Link to the patchset: https://codereview.chromium.org/967323002/#ps100001
(title: "static_cast instead")

[commit-bot: I haz the power, 2015-03-04 12:44:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/967323002/100001

[commit-bot: I haz the power, 2015-03-04 13:15:12]

Committed patchset #6 (id:100001)

[commit-bot: I haz the power, 2015-03-04 13:15:46]

Patchset 6 (id:??) landed as
https://crrev.com/1a608493e55eacf5c7569e2b1213da42eb0e6207
Cr-Commit-Position: refs/heads/master@{#26983}