Judge Samuel A. Alito Jr. completed his testimony at his Supreme Court confirmation hearings on Thursday to a blast of opposition from Democrats, who signaled they would not support him. They also indicated, however, that they saw little chance of blocking his confirmation, even with a filibuster. Several Democratic senators on the Judiciary Committee took the step of announcing, as Judge Alito sat before them, that they had been alienated by his 18 hours of testimony, which left them with doubts about his credibility, as well as deep concern about his record on abortion rights and his views on the...