Add debug-stepnext test for for-let loops

Add debug-stepnext test for for-let loops

Committed: https://crrev.com/a1f20f09282cd395a0f04781fe764c3c38878bc0
Cr-Commit-Position: refs/heads/master@{#29523}

[adamk, 2015-07-01 19:46:21]

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

[Yang, 2015-07-02 08:26:23]

Thank you! LGTM.

[adamk, 2015-07-07 17:45:16]

The CQ bit was checked by adamk@chromium.org

[commit-bot: I haz the power, 2015-07-07 17:45:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1215383002/1

[commit-bot: I haz the power, 2015-07-07 17:46:17]

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

[commit-bot: I haz the power, 2015-07-07 17:46:18]

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/7498)
  v8_linux_arm64_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_arm64_rel/builds/7427)
  v8_mac_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_mac_rel/builds/7505)

(exceeded global retry quota)

[Yang, 2015-07-07 17:49:05]

On 2015/07/07 17:46:18, commit-bot: I haz the power wrote:
> 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/7498)
>   v8_linux_arm64_rel on tryserver.v8 (JOB_FAILED,
>
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_arm64_rel/builds/7427)
>   v8_mac_rel on tryserver.v8 (JOB_FAILED,
> http://build.chromium.org/p/tryserver.v8/builders/v8_mac_rel/builds/7505)
> 
> (exceeded global retry quota)

I landed some changes related to debug stepping lately. Also affecting this test
case.

[adamk, 2015-07-07 18:48:50]

The CQ bit was checked by adamk@chromium.org

[adamk, 2015-07-07 18:48:50]

The patchset sent to the CQ was uploaded after l-g-t-m from yangguo@chromium.org
Link to the patchset: https://codereview.chromium.org/1215383002/#ps20001
(title: "Rebased")

[commit-bot: I haz the power, 2015-07-07 18:49:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1215383002/20001

[commit-bot: I haz the power, 2015-07-07 19:11:32]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-07-07 19:11:48]

Patchset 2 (id:??) landed as
https://crrev.com/a1f20f09282cd395a0f04781fe764c3c38878bc0
Cr-Commit-Position: refs/heads/master@{#29523}