As the defending two-time champions, the Dodgers don’t exactly need litmus tests. Still, this weekend gave them a chance to size up one of their biggest fellow National League contenders — and reaffirm their own status as MLB’s foremost World Series threat once again. After dropping a Friday night series opener to the Cubs that ran Chicago’s win streak to 10 games, the Dodgers bounced back the way title-winning teams are supposed to, cruising to back-to-back victories at Dodger Stadium to rally and take the three-game set. Kyle Tucker went 1-for-3 and scored two runs Sunday against the Cubs. Jonathan Hui-Imagn Images The series was decided Sunday, in a 6-0 Dodgers win keyed by another pitching gem from Justin Wrobleski and another resurgent day from the club’s relentless lineup. Wrobleski spun six scoreless innings in his start, despite battling poor command, heavy traffic and a high pitch count early.…