[IE] Removing background from selected text not working correctly

[Tomasz Jakut]

Steps to reproduce

1. Open ​http://ckeditor.dev/samples.
2. In source mode, set editor's content to:

   <p><span style="background-color: rgb(255,255,0);">Text with background</span></p>
   

3. In WYSIWYG mode, select "with".
4. Open console and paste into it:

   var style = new CKEDITOR.style( {
       element: 'span',
       styles: {
           'background-color': '#ff0'
       },
       type: CKEDITOR.STYLE_INLINE
   } );
   
   style.remove( CKEDITOR.instances.editor );
   

Note that "with" must be still selected inside the editor.

Expected result

Background is removed from the selected text.

Actual result

Background is removed from the entire paragraph.

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

Only in Internet Explorer 9+.

Probably introduced by ​http://github.com/ckeditor/ckeditor-dev/commit/0528e5aaeb104ffd283aeb4ff5efa2fcdb0616e4.