If voters agree to pay for half of a $1 billion stadium, the Texas Rangers will stick around Arlington long enough to celebrate the team’s 80th anniversary. City leaders and Rangers officials formally announced Friday afternoon their plans to extend the Rangers’ stay by building a retractable-roof stadium adjacent to the existing one. The city and team would share the cost evenly, with the Rangers responsible for overruns.The stadium is expected to open no later than the 2021 season, nearly three years before the team’s contract to play at Globe Life Park expires. The team, which moved from Washington to Arlington in 1972, would be committed to the city through the 2053 season.