(CHECK_NATNUM): Use NATNUMP instead of its expansion.

src/xfns.c

@@ -717,9 +717,8 @@ x_set_frame_parameters (f, alist)
 	  param_index = Fget (prop, Qx_frame_parameter);
 	  old_value = get_frame_param (f, prop);
 	  store_frame_param (f, prop, val);
- 	  if (INTEGERP (param_index)
-	      && XINT (param_index) >= 0
-	      && (XINT (param_index)
+ 	  if (NATNUMP (param_index)
+	      && (XFASTINT (param_index)
 		  < sizeof (x_frame_parms)/sizeof (x_frame_parms[0])))
 	    (*x_frame_parms[XINT (param_index)].setter)(f, val, old_value);
 	}