Proper handling of future reserved words in strict and normal mode.

src/messages.js

Index: src/messages.js
diff --git a/src/messages.js b/src/messages.js
index 8da1ca48e7079d8974da215e582c73194ebfe6e8..841c5180a3df0c7d24a82d1b52e56b576454c3b7 100644
--- a/src/messages.js
+++ b/src/messages.js
@@ -148,6 +148,7 @@ function FormatMessage(message) {
       unexpected_token_number:      ["Unexpected number"],
       unexpected_token_string:      ["Unexpected string"],
       unexpected_token_identifier:  ["Unexpected identifier"],
+      unexpected_reserved:          ["Unexpected reserved word"],
       unexpected_strict_reserved:   ["Unexpected strict mode reserved word"],
       unexpected_eos:               ["Unexpected end of input"],
       malformed_regexp:             ["Invalid regular expression: /", "%0", "/: ", "%1"],