[es6] Reintroduce the instanceof operator in the backends.

src/parsing/parser.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_PARSING_PARSER_H_
 #define V8_PARSING_PARSER_H_
 
 #include "src/allocation.h"
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
@@ skipping 659 matching lines @@
   V8_INLINE void RewriteNonPattern(Type::ExpressionClassifier* classifier,
                                    bool* ok);
 
   V8_INLINE Zone* zone() const;
 
   V8_INLINE ZoneList<Expression*>* GetNonPatternList() const;
 
   Expression* RewriteYieldStar(
       Expression* generator, Expression* expression, int pos);
 
-  Expression* RewriteInstanceof(Expression* lhs, Expression* rhs, int pos);
-
  private:
   Parser* parser_;
 
   void BuildIteratorClose(ZoneList<Statement*>* statements, Variable* iterator,
                           Maybe<Variable*> input, Variable* output);
   void BuildIteratorCloseForCompletion(
       ZoneList<Statement*>* statements, Variable* iterator,
       Variable* body_threw);
   Statement* CheckCallable(Variable* var, Expression* error, int pos);
 };
@@ skipping 601 matching lines @@
 
 DoExpression* ParserTraits::ParseDoExpression(bool* ok) {
   return parser_->ParseDoExpression(ok);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_H_