Add Sergio Villar to core/layout OWNERS

Add Sergio Villar to core/layout OWNERS

Sergio has been involved in WebKit / Blink
for a long time.  He is a WebKit reviewer
since February 2014 and has more than 100
patches in WebKit / Blink. Lately he has
handled the layout side of CSS Grid Layout.

NOTRY=true

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196441

[Julien - ping for review, 2015-06-03 22:37:32]

jchaffraix@chromium.org changed reviewers:
+ dsinclair@chromium.org, eae@chromium.org, leviw@chromium.org

[eae, 2015-06-03 22:38:59]

LGTM

[leviw_travelin_and_unemployed, 2015-06-03 22:39:12]

LGTM 2

[eae, 2015-06-03 22:39:26]

The CQ bit was checked by eae@chromium.org

[commit-bot: I haz the power, 2015-06-03 22:40:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1166623007/1

[commit-bot: I haz the power, 2015-06-03 23:07:56]

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

[commit-bot: I haz the power, 2015-06-03 23:07:57]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/6...)

[pdr., 2015-06-03 23:11:59]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2015-06-03 23:12:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1166623007/1

[commit-bot: I haz the power, 2015-06-03 23:29:44]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196441