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

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 554 matching lines @@
   V8_INLINE ZoneList<Statement*>* ParseEagerFunctionBody(
       const AstRawString* name, int pos,
       const ParserFormalParameters& parameters, FunctionKind kind,
       FunctionLiteral::FunctionType function_type, bool* ok);
 
   ClassLiteral* ParseClassLiteral(const AstRawString* name,
                                   Scanner::Location class_name_location,
                                   bool name_is_strict_reserved, int pos,
                                   bool* ok);
 
+  V8_INLINE void MarkTailPosition(Expression* expression);
+
   V8_INLINE void CheckConflictingVarDeclarations(v8::internal::Scope* scope,
                                                  bool* ok);
 
   class TemplateLiteral : public ZoneObject {
    public:
     TemplateLiteral(Zone* zone, int pos)
         : cooked_(8, zone), raw_(8, zone), expressions_(8, zone), pos_(pos) {}
 
     const ZoneList<Expression*>* cooked() const { return &cooked_; }
     const ZoneList<Expression*>* raw() const { return &raw_; }
@@ skipping 662 matching lines @@
 
 DoExpression* ParserTraits::ParseDoExpression(bool* ok) {
   return parser_->ParseDoExpression(ok);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_H_