fix broken webkitpy unittest introduced in r154456.

(missed a reference to the --replay option).

TBR=tonyg@chromium.org, eseidel@chromium.org

Review URL: https://codereview.chromium.org/19726002

git-svn-id: svn://svn.chromium.org/blink/trunk@154460 bbb929c8-8fbe-4397-9dbb-9b2b20218538