[Webkit/Blink] Empty line is removed when changing selection after inline widget removal.

[kkrzton]

Steps to reproduce

1. Go to ​http://ckeditor.com/demo#widgets.
2. Scroll to Mathematical Formulas example.
3. Focus first formula.
4. Remove (e.g. using delete key).
5. Move caret from empty line somewhere else in the editor (using up/down arrows or mouse).

Expected result

The empty line is not removed even after caret is moved.

Actual result

The empty line is removed after caret is moved.

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

Tested on Chrome (50) and Safari (9.1) with CKEditor 4.5.9.

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Slightly different use case:

After removing widget, click outside the editor (nothing happens - empty line stays were it was). Line is removed when editor gains focus again (even if you try to focus on the exact same empty line).