[Widgets] Excessive snapshot is recorder if blurred and focused editor

[Piotrek Koszuliński]

1. Open ​http:///ckeditor.dev/plugins/image2/samples/image2.html
2. Open image dialog. Type any URL and press ok.
3. Click outside editor (select some text).
4. Doubleclick the created widget.
5. Change alignment and press ok.
6. Press CTRL+Z - the previous alignment should be restored (OK).
7. Press CTRL+Z:
   • Expected: the widget should be removed.
   • Actual: You need to press CTRL+Z twice.

The reason why this happens is that initially snapshot contains widget classes in the following order:

 cke_widget_focused cke_widget_selected

Unfortunately, once editor is blurred, the cke_widget_focused class is removed and when it's added back (on editor focus, on doubleclick) it's added at the end.

The solution would be to always add cke_widget_focused class after cke_widget_selected.

Reproduced on Chrome.