[OT] Collect requiredFeature only if features are not provided

As per Werner's report on the list.

src/hb-ot-layout.cc

@@ -446,19 +446,19 @@ _hb_ot_layout_collect_lookups_features (hb_face_t      *face,
 					const hb_tag_t *features,
 					hb_set_t       *lookup_indexes /* OUT */)
 {
-  unsigned int required_feature_index;
-  if (hb_ot_layout_language_get_required_feature_index (face,
-							table_tag,
-							script_index,
-							language_index,
-							&required_feature_index))
-    _hb_ot_layout_collect_lookups_lookups (face,
-					   table_tag,
-					   required_feature_index,
-					   lookup_indexes);
-
   if (!features)
   {
+    unsigned int required_feature_index;
+    if (hb_ot_layout_language_get_required_feature_index (face,
+							  table_tag,
+							  script_index,
+							  language_index,
+							  &required_feature_index))
+      _hb_ot_layout_collect_lookups_lookups (face,
+					     table_tag,
+					     required_feature_index,
+					     lookup_indexes);
+
     /* All features */
     unsigned int feature_indices[32];
     unsigned int offset, len;