Fix bug #9610 with slow cursor motion in buffers with invisible text.

Fix bug #9610 with slow cursor motion in buffers with invisible text.

 src/xdisp.c (handle_invisible_prop): If invisible text ends on a
 newline, reseat the iterator instead of bidi-iterating there one
 character at a time.  (Bug#9610)
 (BUFFER_POS_REACHED_P, move_it_in_display_line_to): Bail when past
 TO_CHARPOS if the bidi iterator is at base embedding level.