Slices not synchronized to canvas resize operations

[whizzter]

When using the "canvas size..." menu the slice elements are not properly moved. (probably a bug also rescaling with "Sprite size...")

Repro
Create any image with a few slices.
Resize canvas with any alignment but upper-left (only tried upscaling)

What happens
Slices are still on their original pixel positions but since the canvas pixels are moved they are now out of sync.

What should happen
Slice's should move with the canvas resize operation.

Aseprite and System version

• Aseprite version: 1.2-beta9 (steam)
• System: Windows 10 Creators Update