(struct buffer): Delete redisplay_end_trigger field.

src/buffer.h

@@ -403,10 +403,6 @@ struct buffer
                  if it is memq in that list.  */
     Lisp_Object invisibility_spec;
 
-    /* If redisplay goes beyond this point in the buffer,
-       run redisplay-end-trigger-hook.  */
-    Lisp_Object redisplay_end_trigger;
-
     /* These are so we don't have to recompile everything
        the next few times we add a new slot.  */
     Lisp_Object extra1, extra2, extra3;