Massage mask setting a bit more

Still finding the exact correct way the masks should be set.

src/hb-buffer-private.hh

diff --git a/src/hb-buffer-private.hh b/src/hb-buffer-private.hh
index 8154b17..585a82a 100644
--- a/src/hb-buffer-private.hh
+++ b/src/hb-buffer-private.hh
@@ -107,6 +107,10 @@
 
 HB_INTERNAL void
 _hb_buffer_add_masks (hb_buffer_t *buffer,
+		      hb_mask_t    mask);
+
+HB_INTERNAL void
+_hb_buffer_set_masks (hb_buffer_t *buffer,
 		      hb_mask_t    value,
 		      hb_mask_t    mask,
 		      unsigned int cluster_start,
@@ -165,12 +169,21 @@
   { _hb_buffer_add_output_glyph (this, glyph_index, component, ligID); }
   inline void replace_glyph (hb_codepoint_t glyph_index) { add_output_glyph (glyph_index); }
 
-  inline void reset_masks (hb_mask_t mask) { _hb_buffer_reset_masks (this, mask); }
-  inline void add_masks (hb_mask_t value,
+  inline void reset_masks (hb_mask_t mask)
+  {
+    for (unsigned int i = 0; i < len; i++)
+      info[i].mask = mask;
+  }
+  inline void add_masks (hb_mask_t mask)
+  {
+    for (unsigned int i = 0; i < len; i++)
+      info[i].mask |= mask;
+  }
+  inline void set_masks (hb_mask_t value,
 			 hb_mask_t mask,
 			 unsigned int cluster_start,
 			 unsigned int cluster_end)
-  { _hb_buffer_add_masks (this, value, mask, cluster_start, cluster_end); }
+  { _hb_buffer_set_masks (this, value, mask, cluster_start, cluster_end); }
 
 };