Do not clear stepping after DebugEvaluate.

Do not clear stepping after DebugEvaluate.

Clearing stepping was originally introduced in http://codereview.chromium.org/7889039
But DebugEvaluate now also uses a DisableBreak scope, which makes sure we don't step
inside the evaluated code.

R=yurys@chromium.org
BUG=chromium:467180
LOG=N

Committed: https://crrev.com/19312c1631c2cade977c6e94398c5b08361bb717
Cr-Commit-Position: refs/heads/master@{#28461}

[Yang, 2015-05-18 06:55:06]

This is the alternative solution to https://codereview.chromium.org/1132643004/
because latter has been reverted.

[Yang, 2015-05-18 06:56:27]

The CQ bit was checked by yangguo@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-05-18 06:56:37]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1129363003/1

[commit-bot: I haz the power, 2015-05-18 07:21:43]

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

[commit-bot: I haz the power, 2015-05-18 07:21:43]

Dry run: This issue passed the CQ dry run.

[yurys, 2015-05-18 22:44:14]

lgtm

[Yang, 2015-05-19 04:54:15]

The CQ bit was checked by yangguo@chromium.org

[commit-bot: I haz the power, 2015-05-19 04:54:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1129363003/1

[commit-bot: I haz the power, 2015-05-19 04:56:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-19 04:56:41]

Patchset 1 (id:??) landed as
https://crrev.com/19312c1631c2cade977c6e94398c5b08361bb717
Cr-Commit-Position: refs/heads/master@{#28461}