remove another Core.Inference call

Author: rdeits

src/gridded/gridded.jl

@@ -28,7 +28,7 @@ function GriddedInterpolation(::Type{TWeights}, knots::NTuple{N,GridIndex}, A::A
     for _ in 2:N
         c *= c
     end
-    T = Core.Inference.return_type(*, Tuple{typeof(c), TCoefs})
+    T = Base.promote_op(*, typeof(c), TCoefs)
 
     GriddedInterpolation{T,N,TCoefs,IT,typeof(knts),pad}(knts, A)
 end