Add get_size to UnsizedArrayOf
diff --git a/src/hb-open-type.hh b/src/hb-open-type.hh
index 00bd134..0625760 100644
--- a/src/hb-open-type.hh
+++ b/src/hb-open-type.hh
@@ -343,6 +343,9 @@
   template <typename T> inline operator  T * (void) { return arrayZ; }
   template <typename T> inline operator const T * (void) const { return arrayZ; }
 
+  inline unsigned int get_size (unsigned int len) const
+  { return len * Type::static_size; }
+
   inline bool sanitize (hb_sanitize_context_t *c, unsigned int count) const
   {
     TRACE_SANITIZE (this);