Roll HarfBuzz to 1.3.0

third_party/harfbuzz-ng/src/hb-ot-layout-gsubgpos-private.hh

Index: third_party/harfbuzz-ng/src/hb-ot-layout-gsubgpos-private.hh
diff --git a/third_party/harfbuzz-ng/src/hb-ot-layout-gsubgpos-private.hh b/third_party/harfbuzz-ng/src/hb-ot-layout-gsubgpos-private.hh
index 56c501533b24ddb9880772edfa18df05907a48de..997d22550547521dd902d712726a1206a38f174a 100644
--- a/third_party/harfbuzz-ng/src/hb-ot-layout-gsubgpos-private.hh
+++ b/third_party/harfbuzz-ng/src/hb-ot-layout-gsubgpos-private.hh
@@ -996,10 +996,13 @@ static inline bool apply_lookup (hb_apply_context_t *c,
 
     /* Recursed lookup changed buffer len.  Adjust. */
 
-    /* end can't go back past the current match position.
-     * Note: this is only true because we do NOT allow MultipleSubst
-     * with zero sequence len. */
-    end = MAX (MIN((int) match_positions[idx] + 1, (int) new_len), int (end) + delta);
+    end = int (end) + delta;
+    if (end <= match_positions[idx])
+    {
+      /* There can't be any further changes. */
+      assert (end == match_positions[idx]);
+      break;
+    }
 
     unsigned int next = idx + 1; /* next now is the position after the recursed lookup. */