Remove zero-width chars in the fallback shaper too

src/hb-fallback-shape.cc

@@ -34,16 +34,24 @@ _hb_fallback_shape (hb_font_t          *font,
 		    const hb_feature_t *features HB_UNUSED,
 		    unsigned int        num_features HB_UNUSED)
 {
+  /* TODO Save the space character in the font? */
+  hb_codepoint_t space;
+  hb_font_get_glyph (font, ' ', 0, &space);
+
   buffer->guess_properties ();
+  buffer->clear_positions ();
 
   unsigned int count = buffer->len;
 
   for (unsigned int i = 0; i < count; i++)
+  {
+    if (_hb_unicode_is_zero_width (buffer->info[i].codepoint)) {
+      buffer->info[i].codepoint = space;
+      buffer->pos[i].x_advance = 0;
+      buffer->pos[i].y_advance = 0;
+      continue;
+    }
     hb_font_get_glyph (font, buffer->info[i].codepoint, 0, &buffer->info[i].codepoint);
-
-  buffer->clear_positions ();
-
-  for (unsigned int i = 0; i < count; i++) {
     hb_font_get_glyph_advance_for_direction (font, buffer->info[i].codepoint,
 					     buffer->props.direction,
 					     &buffer->pos[i].x_advance,