Simplify the `create` method of `Size::class`

The size method exists as a static factory method for Size::class.

Since it is essentially just a simplification of the constructor, it should fully embody that role.

Therefore, it should be possible to pass the pivot point directly using x and y without having to create a new object. Alternatively, pivot objects can still be passed via the constructor.

Before

Size::create(300, 200, new Point(30, 40));

After

Size::create(300, 200, 30, 40);