[es6] Re-implement rest parameters via desugaring.

src/ast-literal-reindexer.h

Index: src/ast-literal-reindexer.h
diff --git a/src/ast-literal-reindexer.h b/src/ast-literal-reindexer.h
index 9e445129a5ecfb9be85ca413f2c44c2f2f222a18..ebfd3914c052837c09e764376aadb78e0d6e7b55 100644
--- a/src/ast-literal-reindexer.h
+++ b/src/ast-literal-reindexer.h
@@ -32,6 +32,10 @@ class AstLiteralReindexer final : public AstVisitor {
     literal->literal_index_ = next_index_++;
   }
 
+  void UpdateIndex(RestParameter* pseudo_literal) {
+    pseudo_literal->literal_index_ = next_index_++;
+  }
+
   void Visit(AstNode* node) override { node->Accept(this); }
 
   int next_index_;