[instancer] reference all points for gvar

If a point is not referenced and delta is not inferred, set delta to 0
diff --git a/src/hb-ot-var-common.hh b/src/hb-ot-var-common.hh
index 0a92e00..d35b10c 100644
--- a/src/hb-ot-var-common.hh
+++ b/src/hb-ot-var-common.hh
@@ -993,8 +993,20 @@
       start_point = end_point + 1;
     }
 
-    for (unsigned i : inferred_idxes)
-      indices[i] = true;
+    for (unsigned i = 0; i < point_count; i++)
+    {
+      /* if points are not referenced and deltas are not inferred, set to 0.
+       * reference all points for gvar */
+      if ( !indices[i])
+      {
+        if (!inferred_idxes.has (i))
+        {
+          deltas_x.arrayZ[i] = 0.f;
+          deltas_y.arrayZ[i] = 0.f;
+        }
+        indices[i] = true;
+      }
+    }
     return true;
   }
 
diff --git a/test/subset/data/expected/glyf_partial_instancing/Roboto-Variable.composite.no-tables-with-item-variations.retain-all-codepoint.wght=200-300-500,wdth=80-90.ttf b/test/subset/data/expected/glyf_partial_instancing/Roboto-Variable.composite.no-tables-with-item-variations.retain-all-codepoint.wght=200-300-500,wdth=80-90.ttf
index 503c755..2e55653 100644
--- a/test/subset/data/expected/glyf_partial_instancing/Roboto-Variable.composite.no-tables-with-item-variations.retain-all-codepoint.wght=200-300-500,wdth=80-90.ttf
+++ b/test/subset/data/expected/glyf_partial_instancing/Roboto-Variable.composite.no-tables-with-item-variations.retain-all-codepoint.wght=200-300-500,wdth=80-90.ttf
Binary files differ
diff --git a/test/subset/data/expected/glyf_partial_instancing/Roboto-Variable.composite.no-tables-with-item-variations.retain-all-codepoint.wght=300-600,wdth=85.ttf b/test/subset/data/expected/glyf_partial_instancing/Roboto-Variable.composite.no-tables-with-item-variations.retain-all-codepoint.wght=300-600,wdth=85.ttf
index 7434335..fc890fb 100644
--- a/test/subset/data/expected/glyf_partial_instancing/Roboto-Variable.composite.no-tables-with-item-variations.retain-all-codepoint.wght=300-600,wdth=85.ttf
+++ b/test/subset/data/expected/glyf_partial_instancing/Roboto-Variable.composite.no-tables-with-item-variations.retain-all-codepoint.wght=300-600,wdth=85.ttf
Binary files differ