Empty spans not being removed

[Marek Lewandowski]

occures at current master, was not present in 4.3 release

Extra, empty span is left in certian situations

1. open any sample with CKEditor (i.e. samples/replacebyclass.html)
2. set source to following html

   <h3>Type the title here</h3>
   
   <p>Type the text here</p>
   

3. go back to wysiwyg mode
4. open search dialog
5. type the text in find textfield
6. click find
7. press esc

--- note already you have extra span left ---

You may now move cursor elsewhere and go back to the text substring, and span will still be there.

Expected result:
Produced source code:

<h3>Type the title here</h3>

<p>Type the text here</p>

Current result:
Code has extra span:

<h3>Type the title here</h3>

<p>Type <span>the text</span> here</p>

additional info:

1. you can insert multiple ammount of spans, by clicking find multiple times, none of them will be cleaned
2. i've reproduced it witch chrome and firefox