Fix stack-use-after-return in ~ScopeRecorder

Fix stack-use-after-return in ~ScopeRecorder

We should not save the reference to a temporary DisplayItemClientWrapper
in ScopeRecorder.

BUG=501721
R=chrishtr@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197396

[Xianzhu, 2015-06-18 19:28:05]

wangxianzhu@chromium.org changed reviewers:
+ chrishtr@chromium.org

[chrishtr, 2015-06-18 19:30:02]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2015-06-18 19:30:03]

lgtm

[commit-bot: I haz the power, 2015-06-18 19:31:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1194673005/1

[commit-bot: I haz the power, 2015-06-18 21:10:33]

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

[commit-bot: I haz the power, 2015-06-18 21:10:34]

Try jobs failed on following builders:
  mac_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/59602)

[Xianzhu, 2015-06-18 21:14:45]

The CQ bit was checked by wangxianzhu@chromium.org

[commit-bot: I haz the power, 2015-06-18 21:16:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1194673005/1

[Xianzhu, 2015-06-18 21:18:00]

Committed patchset #1 (id:1) manually as 197396 (presubmit successful).