fix(parse): permit unbraced function expression as for's next

Author: JohelEGP

source/parse.h

@@ -4060,9 +4060,10 @@ class parser
                     && curr().type() != lexeme::LeftParen               // not imediatelly called
                     && curr().type() != lexeme::RightParen              // not as a last argument to function
                     && curr().type() != lexeme::Comma                   // not as first or in-the-middle, function argument
-                    && curr().type() != lexeme::RightBracket            // as the last index argument
-                    && curr().as_string_view() == "is"                  // as the argument to is
-                    && curr().as_string_view() == "as"                  // as the argument to as
+                    && curr().type() != lexeme::RightBracket            // not as the last index argument
+                    && curr() != "is"                                   // not as the argument to is
+                    && curr() != "as"                                   // not as the argument to as
+                    && curr() != "do"                                   // not as `for`'s `next`.
                 ) {
                     // this is a fix for a short function syntax that should have double semicolon used
                     // (check comment in expression_statement(bool semicolon_required))