Undo button remains disabled if resizing an already loaded image as first action

[Wizard]

Steps to reproduce ¶

1. Load a ckeditor instance which initially has some text and images
2. Resize an image (1st action) before changing the text.

Expected result ¶

The undo button should be enabled so we can undo the resizing

Actual result ¶

The undo button is disabled. If I then change some text (2nd action), the undo button becomes active and I can undo the 2nd action and then the 1st action.

Other details (browser, OS, CKEditor version, installed plugins) ¶

You can see it in the demo, too (​http://ckeditor.com/demo)

[Jakub Ś]

I will mark this issue as duplicate of #10979 and add your comment there.