Autoembed: undo deletes content typed after pasting autoembeddable link

[Szymon Cofalik]

Steps to reproduce:

1. Write some text.
2. Paste https://www.google.dk/maps/place/Zygmunta+S%C5%82omi%C5%84skiego+15,+Warszawa
3. While autoembedded content is loading, type more text.
4. Autoembedded content is inserted.
5. Undo.

Expected result: Only link convertion should be undone, so the editor should contain some text, the link and the text typed in step 3.

Result: Not only link covertion was undone but also all the text typed in step 3 is deleted.

Note: This can't be tested in Firefox because after pasting the link the caret is "inside" <a> element, so everything what we type is removed when the link is converted to embedded content.

[Szymon Cofalik]

Might be fixed by #13429 (see comment 5)

[Jakub Ś]

Tested on Firefox.

CKEditor 4.5.0-4.5.2: the result is text text embed_content
CKEditor 4.5.3: the result is text embed_content text.

CKEditor 4.5.0-4.5.2: Result is as described by @scofalik.
CKEditor 4.5.3: Result is also as described but you need to press Undo/Ctrl+Z two or three times to actually undo the embed content. If you press once and wait the embed content gets recreated.

NOTE: in my test I have just typed letters and space. I have not used Enter Key. After all when typing text and inserting a link I would expect editor to insert embed content and put selection behind it and not leaving it as it is.