[vector] Always 0-fill new items
diff --git a/src/hb-private.hh b/src/hb-private.hh
index ac00e02..32e3354 100644
--- a/src/hb-private.hh
+++ b/src/hb-private.hh
@@ -716,6 +716,9 @@
     if (!alloc (size))
       return false;
 
+    if (size > len)
+      memset (arrayZ + len, 0, (size - len) * sizeof (*arrayZ));
+
     len = size;
     return true;
   }