Mark Shields, the longtime political commentator who was a decades-long fixture on “PBS Newshour,” died Saturday at age 85. News of his death was shared on Twitter by Newshour anchor Judy Woodruff. “I am heartbroken to share this,” she said in the tweet, stating that for decades, Shields “wowed us with his encyclopedic knowledge of American politics, his sense of humor and mainly his big heart.” She said he died with his wife Anne at his side. Shields first appeared on “The MacNeil/Lehrer NewsHour” during the 1988 presidential election and became a weekly guest. From 2001 to his retirement in...