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

Review URL: https://codereview.chromium.org/1166623007

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@196441 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk