Remove tony@chromium from OWNERS

As noted here, tony does not work on chromium/blink:
https://codereview.chromium.org/291303004/#msg11

This is a followup to https://src.chromium.org/viewvc/blink?view=rev&revision=174825

NOTRY=true

Review URL: https://codereview.chromium.org/303543002

git-svn-id: svn://svn.chromium.org/blink/trunk@174873 bbb929c8-8fbe-4397-9dbb-9b2b20218538