Add Florin Malita as a Source/core OWNER

Florin has enough support, lets make it true!

NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/19807006

git-svn-id: svn://svn.chromium.org/blink/trunk@154694 bbb929c8-8fbe-4397-9dbb-9b2b20218538