src/vs/editor/common/core/rgba.ts/RGBA8/constructor
class RGBA8:	constructor(r: number, g: number, b: number, a: number) {
		this.r = RGBA8._clamp(r);
		this.g = RGBA8._clamp(g);
		this.b = RGBA8._clamp(b);
		this.a = RGBA8._clamp(a);
	}