DUBLIN — An abortion debate that has inflamed passions in Ireland for decades will come down to a single question Friday: Yes or no? The referendum on whether to repeal the country’s strict anti-abortion law is being seen by anti-abortion activists as a last-ditch stand against what they view as a European norm of abortion-on-demand, while for pro-abortion rights advocates, it is a fundamental moment for declaring an Irish woman’s right to choose. If the “yes” side prevails and the constitutional ban on abortions is repealed, the government plans to introduce legislation that would allow abortion within the first 12 weeks of pregnancy, and later in specific cases when the woman is at grave risk or the fetus is likely to die in the womb or shortly after birth.