A prequel nobody asked for to a spin-off nobody needed, “ Annabelle: Creation ” fills in the demonic backstory for the creepy doll seen in “The Conjuring.” Sort of. Instead of enriching this universe in any meaningful way, director David F. Sandberg ’s gimmick-driven nail-biter effectively serves just to push the $800 million franchise past the $1 billion mark. Debuting at the Los Angeles Film Festival nearly two months prior to its Aug. 11 release, this effective yet empty-headed horror movie goes to show how eager audiences are to be scared, and how even an unsightly doll can do the trick when the spirit is willing. Working backwards in time, this fourth film in producer James Wan’s fast-expanding “The Conjuring” franchise (which already has two more installments on the way) takes place in the mid-’50s, following a 12-years-earlier prologue through which we discover the tragedy that inspired heartbroken dollmaker Samuel Mullins (Anthony LaPaglia) and his bedridden wife (Mirando Otto) to invite half a dozen vulnerable orphans into their home. How could the couple have known that their dead daughter has no intention of sharing her toys? And would it even be an issue if these new guests would mind […]