Fix display when left-fringe/right-fringe display spec is invalid.

 src/xdisp.c (handle_single_display_spec): Return 1 for left-margin
 and right-margin display specs even if the spec is invalid or we
 are on a TTY, and thus unable to display on the fringes.  That's
 because the text with the property will not be displayed anyway,
 so we need to signal to the caller that this is a "replacing"
 display spec.  This fixes display when the spec is invalid or we
 are on a TTY.

src/ChangeLog

+2012-05-11  Eli Zaretskii  <eliz@gnu.org>
+
+	* xdisp.c (handle_single_display_spec): Return 1 for left-margin
+	and right-margin display specs even if the spec is invalid or we
+	are on a TTY, and thus unable to display on the fringes.  That's
+	because the text with the property will not be displayed anyway,
+	so we need to signal to the caller that this is a "replacing"
+	display spec.  This fixes display when the spec is invalid or we
+	are on a TTY.
+
 2012-05-09  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* unexaix.c (make_hdr): Fix typo in prototype.

src/xdisp.c

@@ -4681,10 +4681,10 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
 	  if (!FRAME_WINDOW_P (it->f))
 	    /* If we return here, POSITION has been advanced
 	       across the text with this property.  */
-	    return 0;
+	    return 1;
 	}
       else if (!frame_window_p)
-	return 0;
+	return 1;
 #ifdef HAVE_WINDOW_SYSTEM
       value = XCAR (XCDR (spec));
@@ -4692,7 +4692,7 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
 	  || !(fringe_bitmap = lookup_fringe_bitmap (value)))
 	/* If we return here, POSITION has been advanced
 	   across the text with this property.  */
-	return 0;
+	return 1;
       if (it)
 	{