getAbsolutePosition don't work with rotation

[GMartigny]

Infos

Your current navigator: Chrome v65
The package you used: @pencil.js/container

Description

The function getAbsolutePosition returns wrong position when the container is nested inside another with a rotation.

Reproduce by

const parent = new Container([0, 0], {
  rotation: 0.5,
});
const child = new Container([10, 10]);
parent.add(child);

child.getAbsolutePosition(); // => fail