The campaign for an open seat on Oregon’s highest court has taken an unusually combative tone. The two candidates — Multnomah County Circuit Judge Richard Baldwin and Portland attorney Nena Cook — are taking potshots at each other over their experience. They have even tried to one-up each other over their up-from-under, working-class backgrounds. The winner will replace Justice Robert “Skip” Durham, who is retiring after 18 years on the bench. Baldwin, who has been a judge for 11 years, has blasted Cook, 46, for inflating her resume, saying she exaggerated her experience prosecuting criminal cases in the Multnomah County …