Meanwhile, reserve tops of 2 of the green onions; slice remaining onions. In large resealable food-storage plastic bag, mix flour, allspice and garlic powder. Add chicken to bag; seal and shake to coat chicken with spices. In 10-inch nonstick skillet, heat oil over medium-high heat. Cook chicken and sliced onions in oil 3 to 4 minutes, turning chicken once, until no longer pink in center. Add pineapple and cooked rice to skillet with chicken. Cook and stir 1 minute or until pineapple is hot.