function getCubeFaceOrder(gl, options) {
  options = options || {};
  return options.cubeFaceOrder || [TEXTURE_CUBE_MAP_POSITIVE_X, TEXTURE_CUBE_MAP_NEGATIVE_X, TEXTURE_CUBE_MAP_POSITIVE_Y, TEXTURE_CUBE_MAP_NEGATIVE_Y, TEXTURE_CUBE_MAP_POSITIVE_Z, TEXTURE_CUBE_MAP_NEGATIVE_Z];
}
Gets an array of cubemap face enums
@param {WebGLRenderingContext} gl the WebGLRenderingContext
@param {module:twgl.TextureOptions} options A TextureOptions object with whatever parameters you want set.
  This is often the same options you passed in when you created the texture.
@return {number[]} cubemap face enums
@private