[es6] early error when Identifier is an escaped reserved word

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index b54172f72c21cc6ccf320ed04877227804a5d134..63ef265fe7c063164c5cf757a1d4c6c49ed0caee 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -1425,6 +1425,9 @@ Statement* Parser::ParseStatementListItem(bool* ok) {
         return ParseVariableStatement(kStatementListItem, NULL, ok);
       }
       break;
+    case Token::IDENTIFIER:
+      CheckNextEscapedKeyword(CHECK_OK);
+      break;
     default:
       break;
   }