Rect absoluteScale incorrect when a negative X scale is applied, also affects transformer anchors

[MadeByMike]

Apply a negative X scale to a rect:

const rect = new Konva.Rect({
  ...
  scale:{
    x: -1,
    y: 1
  }
 });
 
console.log(rect.getAbsoluteScale()) // { x: 1, y: -1 }

The absolute scale will be inverted.

It also impacts transformer handles. Add the item to a transformer and the handles will be flipped. This doesn't happen with a negative Y scale or with multi-selection.

I've created a pen with a demo of this bug: https://codepen.io/MadeByMike/pen/Jjzrymj/b4866fd662e3878546ad52bd999c0f1f

It feels somewhat related to this old issue: #983 but there is no rotation involved. Logging the rotation of every item on the stage shows all to be 0 unless inside a transformer.

I think the behavior of the transformer should be consistent with multi-item selection, in that, the anchors should only change if the transformer itself is rotated or scaled.

[lavrton]

For now, I don't know what will be the solution. getAbsoluteScale() is using transformation matrix decomposition. And this is how the current implementation works. Visually, { x: 1, y: -1 } and { x: -1, y: 1 } looks the same.