Need method *(::SparseMatrixCSC, ::Diagonal)

[sglyon]

julia> X = speye(3)
3x3 sparse matrix with 3 Float64 entries:
    [1, 1]  =  1.0
    [2, 2]  =  1.0
    [3, 3]  =  1.0

julia> y = Diagonal([1.0, 2.0, 3.0])
3x3 Diagonal{Float64}:
 1.0  0.0  0.0
 0.0  2.0  0.0
 0.0  0.0  3.0

julia> X*y
ERROR: MethodError: `*` has no method matching *(::SparseMatrixCSC{Float64,Int64}, ::Diagonal{Float64})
Closest candidates are:
  *(::Any, ::Any, ::Any, ::Any...)
  *{T<:Number}(::T<:Number, ::Diagonal{T})
  *(::Diagonal{T}, ::Diagonal{T})
  ...

[jiahao]

Ref: #8001