function rgb2hex(rgb) {
    return (((rgb[0] * 255) << 16) + ((rgb[1] * 255) << 8) + (rgb[2] * 255 | 0));
}
Converts a color as an [R, G, B] array of normalized floats to a hexadecimal number.
@example
PIXI.utils.rgb2hex([1, 1, 1]); // returns 0xffffff
@memberof PIXI.utils
@function rgb2hex
@param {number[]} rgb - Array of numbers where all values are normalized floats from 0.0 to 1.0.
@returns {number} Number in hexadecimal.