S390: [debugger] simplify debug stepping.

S390: [debugger] simplify debug stepping.

Port 3e2d60d853cdfe49d4db0040b51f75b214a01714

R=yangguo@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com, bjaideep@ca.ibm.com

BUG=
LOG=N

Committed: https://crrev.com/c304d414d837c665c2d5ee6231269eeced986686
Cr-Commit-Position: refs/heads/master@{#37014}

[john.yan, 2016-06-15 18:30:01]

PTAL

[JaideepBajwa, 2016-06-15 18:31:24]

lgtm

[john.yan, 2016-06-15 18:31:42]

The CQ bit was checked by jyan@ca.ibm.com

[commit-bot: I haz the power, 2016-06-15 18:32:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2069193003/1

[commit-bot: I haz the power, 2016-06-15 18:58:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-06-15 19:01:16]

Description was changed from

==========
S390: [debugger] simplify debug stepping.

Port 3e2d60d853cdfe49d4db0040b51f75b214a01714

R=yangguo@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com,
michael_dawson@ca.ibm.com, mbrandy@us.ibm.com, bjaideep@ca.ibm.com

BUG=
LOG=N
==========

to

==========
S390: [debugger] simplify debug stepping.

Port 3e2d60d853cdfe49d4db0040b51f75b214a01714

R=yangguo@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com,
michael_dawson@ca.ibm.com, mbrandy@us.ibm.com, bjaideep@ca.ibm.com

BUG=
LOG=N

Committed: https://crrev.com/c304d414d837c665c2d5ee6231269eeced986686
Cr-Commit-Position: refs/heads/master@{#37014}
==========

[commit-bot: I haz the power, 2016-06-15 19:01:17]

Patchset 1 (id:??) landed as
https://crrev.com/c304d414d837c665c2d5ee6231269eeced986686
Cr-Commit-Position: refs/heads/master@{#37014}