matrixMultiply(a, b) {
    let a00 = a[0 * 3 + 0];
    let a01 = a[0 * 3 + 1];
    let a02 = a[0 * 3 + 2];
    let a10 = a[1 * 3 + 0];
    let a11 = a[1 * 3 + 1];
    let a12 = a[1 * 3 + 2];
    let a20 = a[2 * 3 + 0];
    let a21 = a[2 * 3 + 1];
    let a22 = a[2 * 3 + 2];
    let b00 = b[0 * 3 + 0];
    let b01 = b[0 * 3 + 1];
    let b02 = b[0 * 3 + 2];
    let b10 = b[1 * 3 + 0];
    let b11 = b[1 * 3 + 1];
    let b12 = b[1 * 3 + 2];
    let b20 = b[2 * 3 + 0];
    let b21 = b[2 * 3 + 1];
    let b22 = b[2 * 3 + 2];

    return [
      a00 * b00 + a01 * b10 + a02 * b20,
      a00 * b01 + a01 * b11 + a02 * b21,
      a00 * b02 + a01 * b12 + a02 * b22,
      a10 * b00 + a11 * b10 + a12 * b20,
      a10 * b01 + a11 * b11 + a12 * b21,
      a10 * b02 + a11 * b12 + a12 * b22,
      a20 * b00 + a21 * b10 + a22 * b20,
      a20 * b01 + a21 * b11 + a22 * b21,
      a20 * b02 + a21 * b12 + a22 * b22
    ];
  }
@memberof Proton#Proton.WebGLUtil
@method matrixMultiply

@todo add description
@todo add a, b description
@todo add return description

@param {Object} a
@param {Object} b

@return {Object}