Change event is fired once on arrow consequent to printable letter

[Marek Lewandowski]

An extra change event will be fired when an arrow press is following a printable char.

1. Open any sample with CKEditor (i.e. samples/replacebyclass.html)
2. Add a change event listener, eg:

   CKEDITOR.instances.editor1.on( 'change', function( evt ) {
   	console.log( 'change', evt );
   } );
   

3. Focus the editor, press f so f letter is inserted. Note that at this point we have one change event, which is correct.
4. Press right arrow.

Expected result:
change event is being fired.

Current result:
No change event should be fired.

This is an regression, was not seen in 4.4.3.

additional info:

1. Only one extra change event will be fired that way.
2. Checked in FF, Chrome, IE8

[Marek Lewandowski]

dup of #12300