Fix webkitpy unittest update missed in https://codereview.chromium.org/58533003.

TBR=eae@chromium.org

Review URL: https://codereview.chromium.org/58203004

git-svn-id: svn://svn.chromium.org/blink/trunk@161297 bbb929c8-8fbe-4397-9dbb-9b2b20218538