Parse 'super' keyword.

src/messages.js

Index: src/messages.js
diff --git a/src/messages.js b/src/messages.js
index eba1e16ece04e8603ff1ca67a5e9ab8ddcaec061..d98fe4841217c8260951862d28fb842ac9e21565 100644
--- a/src/messages.js
+++ b/src/messages.js
@@ -167,7 +167,8 @@ var kMessages = {
   symbol_to_number:              ["Cannot convert a Symbol value to a number"],
   invalid_module_path:           ["Module does not export '", "%0", "', or export is not itself a module"],
   module_type_error:             ["Module '", "%0", "' used improperly"],
-  module_export_undefined:       ["Export '", "%0", "' is not defined in module"]
+  module_export_undefined:       ["Export '", "%0", "' is not defined in module"],
+  unexpected_super:              ["'super' keyword unexpected here"]
 };