Tileset Physics Layer Painting doesn't update moved points

### Tested versions

- v4.3.stable.official [77dcf97d8]

### System information

Windows 7 (6.1.7601) - GLES3 (Compatibility) - GeForce 8600 GTS () - Intel(R) Core(TM) i5-4570 CPU @ 3.20GHz (4 Threads)

### Issue description

When editing physics layers collision shapes zoomed, if you move a point the point is not updated on the tile.
Un-zooming the tile and then re-zooming in shows that changes to points placed were not updated.
After reselecting the tile and re-zooming you can edit points and those edits stick.
Images to show the issue:
First the zoomed tile showing the original points placed:
Next: physics layer with points edited:
Notice that the tile image has not updated its points.
Un-zooming (or un-expanding) at this point will lose those changes in points.
When the tile is reselected and re-expanded then the points can be edited and those changes kept.

### Steps to reproduce

1. Select a tile from a tileset. Make sure there exists a physics layer.
2. Select the physics layer and expand the editor.
3. Select original points to make a polygon.
4. Edit/move the original points.
5. Un-expand the editor.
6. Re-expand the editor and you will notice the edits/moves have been lost.

### Minimal reproduction project (MRP)

No MRP.