src/vs/base/common/color.ts/RGBA/constructor
class RGBA:	constructor(r: number, g: number, b: number, a: number = 1) {
		this.r = Math.min(255, Math.max(0, r)) | 0;
		this.g = Math.min(255, Math.max(0, g)) | 0;
		this.b = Math.min(255, Math.max(0, b)) | 0;
		this.a = roundFloat(Math.max(Math.min(1, a), 0), 3);
	}