src/vs/base/common/color.ts/HSLA/toRGBA
class HSLA:	static toRGBA(hsla: HSLA): RGBA {
		const h = hsla.h / 360;
		const { s, l, a } = hsla;
		let r: number, g: number, b: number;

		if (s === 0) {
			r = g = b = l; // achromatic
		} else {
			const q = l < 0.5 ? l * (1 + s) : l + s - l * s;
			const p = 2 * l - q;
			r = HSLA._hue2rgb(p, q, h + 1 / 3);
			g = HSLA._hue2rgb(p, q, h);
			b = HSLA._hue2rgb(p, q, h - 1 / 3);
		}

		return new RGBA(Math.round(r * 255), Math.round(g * 255), Math.round(b * 255), a);
	}