Multidimensional JS Array System.Int32 not found

When using the .cs below to declare and populate multidimensional javascript arrays, I get this error:

MissingFieldException: Field 'System.Int32[,,].' not found.

Here's a brief js that declares and populates one entry:

var multid;

Here is my .cs:

using UnityEngine;

public class MultiDim : MonoBehaviour {
    public static bool[,,] BoolArray (int a, int b, int c) {
        return new bool[a,b,c];
    public static int[,,] IntArray (int a, int b, int c) {
        return new int[a,b,c];

The point of using MultiDim, as described in the documentation, is that the variable is typed correctly using type inference, so doing

var multid;

is wrong, because that's dynamic typing. It needs to be

var multid = MultiDim.IntArray(10,10,10);