[es6] Reintroduce the instanceof operator in the backends.

src/parsing/preparser.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_PREPARSER_H
 #define V8_PARSING_PREPARSER_H
 
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
 #include "src/hashmap.h"
@@ skipping 974 matching lines @@
                                 bool* ok);
 
   inline PreParserExpression RewriteAwaitExpression(PreParserExpression value,
                                                     int pos);
 
   V8_INLINE Zone* zone() const;
   V8_INLINE ZoneList<PreParserExpression>* GetNonPatternList() const;
 
   inline PreParserExpression RewriteYieldStar(
       PreParserExpression generator, PreParserExpression expr, int pos);
-  inline PreParserExpression RewriteInstanceof(PreParserExpression lhs,
-                                               PreParserExpression rhs,
-                                               int pos);
 
  private:
   PreParser* pre_parser_;
 };
 
 
 // Preparsing checks a JavaScript program and emits preparse-data that helps
 // a later parsing to be faster.
 // See preparse-data-format.h for the data format.
 
@@ skipping 217 matching lines @@
 ZoneList<PreParserExpression>* PreParserTraits::GetNonPatternList() const {
   return pre_parser_->function_state_->non_patterns_to_rewrite();
 }
 
 
 PreParserExpression PreParserTraits::RewriteYieldStar(
     PreParserExpression generator, PreParserExpression expression, int pos) {
   return PreParserExpression::Default();
 }
 
-PreParserExpression PreParserTraits::RewriteInstanceof(PreParserExpression lhs,
-                                                       PreParserExpression rhs,
-                                                       int pos) {
-  return PreParserExpression::Default();
-}
-
 PreParserStatementList PreParser::ParseEagerFunctionBody(
     PreParserIdentifier function_name, int pos,
     const PreParserFormalParameters& parameters, FunctionKind kind,
     FunctionLiteral::FunctionType function_type, bool* ok) {
   ParsingModeScope parsing_mode(this, PARSE_EAGERLY);
 
   Scope* inner_scope = scope_;
   if (!parameters.is_simple) inner_scope = NewScope(scope_, BLOCK_SCOPE);
 
   {
@@ skipping 12 matching lines @@
     const PreParserFormalParameters& parameters, FunctionKind kind,
     FunctionLiteral::FunctionType function_type, bool* ok) {
   return pre_parser_->ParseEagerFunctionBody(function_name, pos, parameters,
                                              kind, function_type, ok);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PREPARSER_H