The mother of the 8-year-old who was killed at his birthday party is begging other parents to avoid buying this one common decoration that killed her little boy in “one of the most tragic of accidents.” Little Joshua Dunbar, a bright-eyed 8-year-old full of energy and dreams, had just celebrated his birthday. The house was filled with balloons, party hats, and all the little joys that come with turning another year older. But just hours after the laughter faded, tragedy…