TORONTO — What you want when the next four are against the Boston Celtics, Los Angeles Lakers, Phoenix Suns and Cleveland Cavaliers is some sort of cushion. The Miami Heat squandered the opportunity Sunday night with a 119-116 loss at Scotiabank Arena to the lowly Toronto Raptors, a loss that dropped them to 9-9. On this night, even mediocrity proved to be a struggle, which is all that might have been required against an opponent that improved to 6-15. Instead, the Heat proved unable to double up on Friday night’s 121-111 victory over the Raptors at Kaseya Center, dominated in the paint by the Raptors and dominated on the scoreboard by Toronto forward R.J.