* xfaces.c (face_at_buffer_position): New arg base_face_id.

* xfaces.c (face_at_buffer_position): New arg base_face_id.

* xdisp.c (handle_face_prop): Pass base_face_id of iterator to
face_at_buffer_position.
(face_before_or_after_it_pos, get_next_display_element)
(note_mouse_highlight): Update face_at_buffer_position call.

* term.c (term_mouse_highlight):
* msdos.c (IT_note_mouse_highlight):
* fontset.c (Finternal_char_font):
* font.c (font_at, font_range): Update face_at_buffer_position
call.

* dispextern.h (face_at_buffer_position): Update prototype.