g.Rect.fromPointUnion(...points)

Returns a new rectangle object that is large enough to contain given points, where each point is an object with x and y properties. Examples:

const rect = g.Rect.fromPointUnion(new g.Point(0, 0), new g.Point(20, 20));
const rect2 = g.Rect.fromPointUnion({ x: 0, y: 0 }, { x: 20, y: 20 });
// { x: 0, y: 0, width: 20, height: 20 }