For-of statements do not permit initializers.

src/parser.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 711 matching lines @@
       // Any further calls to Next or peek will return the illegal token.
       // The current call must return the next token, which might already
       // have been peek'ed.
       stack_overflow_ = true;
     }
     return scanner().Next();
   }
 
   bool is_generator() const { return current_function_state_->is_generator(); }
 
-  bool CheckInOrOf(ForEachStatement::VisitMode* visit_mode);
+  bool CheckInOrOf(bool accept_OF, ForEachStatement::VisitMode* visit_mode);
 
   bool peek_any_identifier();
 
   INLINE(void Consume(Token::Value token));
   void Expect(Token::Value token, bool* ok);
   bool Check(Token::Value token);
   void ExpectSemicolon(bool* ok);
   bool CheckContextualKeyword(Vector<const char> keyword);
   void ExpectContextualKeyword(Vector<const char> keyword, bool* ok);
 
@@ skipping 159 matching lines @@
  private:
   static const int kLiteralTypeSlot = 0;
   static const int kElementsSlot = 1;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(CompileTimeValue);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PARSER_H_