[aat] Always generate a feature range

src/hb-aat-map.cc

@@ -85,14 +85,16 @@ void
 hb_aat_map_builder_t::compile (hb_aat_map_t  &m)
 {
   /* Compute active features per range, and compile each. */
-  if (features.length)
-  {
+
   /* Sort features by start/end events. */
   hb_vector_t<feature_event_t> feature_events;
   for (unsigned int i = 0; i < features.length; i++)
   {
     auto &feature = features[i];
 
+    if (features[i].start == features[i].end)
+      continue;
+
     feature_event_t *event;
 
     event = feature_events.push ();
@@ -112,7 +114,7 @@ hb_aat_map_builder_t::compile (hb_aat_map_t  &m)
     feature.seq = features.length + 1;
 
     feature_event_t *event = feature_events.push ();
-      event->index = 0; /* This value does magic. */
+    event->index = -1; /* This value does magic. */
     event->start = false;
     event->feature = feature;
   }
@@ -160,7 +162,6 @@ hb_aat_map_builder_t::compile (hb_aat_map_t  &m)
 	active_features.remove_ordered (feature - active_features.arrayZ);
     }
   }
-  }
 }