static getScaling_(out, mat) {
    const m11 = mat[0];
    const m12 = mat[1];
    const m13 = mat[2];
    const m21 = mat[4];
    const m22 = mat[5];
    const m23 = mat[6];
    const m31 = mat[8];
    const m32 = mat[9];
    const m33 = mat[10];

    out[0] = Math.sqrt(m11 * m11 + m12 * m12 + m13 * m13);
    out[1] = Math.sqrt(m21 * m21 + m22 * m22 + m23 * m23);
    out[2] = Math.sqrt(m31 * m31 + m32 * m32 + m33 * m33);
  }
Returns the scaling factor component of a transformation
matrix. If a matrix is built with fromRotationTranslationScale
with a normalized Quaternion parameter, the returned vector will be
the same as the scaling vector
originally supplied.
@param  {!Float32Array} out Vector to receive scaling factor component
@param  {!Float32Array} mat Matrix to be decomposed (input)
@private