Joshua Molina, an 18-month-old boy at first reported as the victim of a house fire, in fact died of stab wounds in the chest, the Los Angeles County coroner’s office reported. Stephanie Molina, 28, the mother, also suffered chest wounds and was reported in serious but stable condition at Harbor-UCLA Medical Center. Detective Joan Wolfe of the Los Angeles Police Department said there were no suspects in the case. Los Angeles Fire Department investigators said the fire, which partly burned the Molina house at 1543 West 213th St. on Saturday afternoon, was deliberately set. Witnesses said the mother was carried from the smoke-filled house by a passer-by, who then returned and found the boy.