Fix WATCHLIST and add a presubmit check that the watchlist actually works

BUG=none
R=dpranke@chromium.org

Review URL: https://codereview.chromium.org/59083006

git-svn-id: svn://svn.chromium.org/blink/trunk@161430 bbb929c8-8fbe-4397-9dbb-9b2b20218538