[es6] Fix tail call elimination in single-expression arrow functions.

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 869 matching lines @@
       PreParserIdentifier name, Scanner::Location function_name_location,
       FunctionNameValidity function_name_validity, FunctionKind kind,
       int function_token_position, FunctionLiteral::FunctionType type,
       LanguageMode language_mode, bool* ok);
 
   PreParserExpression ParseClassLiteral(PreParserIdentifier name,
                                         Scanner::Location class_name_location,
                                         bool name_is_strict_reserved, int pos,
                                         bool* ok);
 
+  V8_INLINE void MarkExpressionInTailPosition(PreParserExpression) {}
+
   PreParserExpressionList PrepareSpreadArguments(PreParserExpressionList list) {
     return list;
   }
 
   inline void MaterializeUnspreadArgumentsLiterals(int count);
 
   inline PreParserExpression SpreadCall(PreParserExpression function,
                                         PreParserExpressionList args, int pos);
 
   inline PreParserExpression SpreadCallNew(PreParserExpression function,
@@ skipping 269 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