function mapTextureMapping( texture, mapping ) {

	if ( mapping === EquirectangularReflectionMapping ) {

		texture.mapping = CubeReflectionMapping;

	} else if ( mapping === EquirectangularRefractionMapping ) {

		texture.mapping = CubeRefractionMapping;

	}

}
This function makes sure the generated cube map uses the correct
texture mapping that corresponds to the equirectangular original.

@private
@param {Texture} texture - The cube texture.
@param {number} mapping - The original texture mapping.