[es7] implement |do| expressions proposal

src/rewriter.h

 // Copyright 2011 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_REWRITER_H_
 #define V8_REWRITER_H_
 
 namespace v8 {
 namespace internal {
 
+class AstValueFactory;
+class DoExpression;
 class ParseInfo;
+class Parser;
 
 class Rewriter {
  public:
   // Rewrite top-level code (ECMA 262 "programs") so as to conservatively
   // include an assignment of the value of the last statement in the code to
   // a compiler-generated temporary variable wherever needed.
   //
   // Assumes code has been parsed and scopes have been analyzed.  Mutates the
   // AST, so the AST should not continue to be used in the case of failure.
   static bool Rewrite(ParseInfo* info);
+
+  // Rewrite a list of statements, using the same rules as a top-level program,
+  // to  ensure identical behaviour of completion result.
+  static bool Rewrite(Parser* parser, DoExpression* expr,
+                      AstValueFactory* factory);
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REWRITER_H_