function parseSide (side) {
  switch (side) {
    case 'back': {
      return THREE.BackSide;
    }
    case 'double': {
      return THREE.DoubleSide;
    }
    default: {
      // Including case `front`.
      return THREE.FrontSide;
    }
  }
}
Return a three.js constant determining which material face sides to render
based on the side parameter (passed as a component property).

@param {string} [side=front] - `front`, `back`, or `double`.
@returns {number} THREE.FrontSide, THREE.BackSide, or THREE.DoubleSide.