I just fixed this after several hours of research.
If one need to do the same thing, he must edit file wp-includes\js\media-views.js
and replace add
with unshift
in this line (#2611, galleryAddToolbar):
edit.get('library').add( state.get('selection').models );
So the code will look like this:
edit.get('library').unshift( state.get('selection').models );
After that when you add images in the gallery they will appear at the top.