[es6] Re-implement rest parameters via desugaring.

src/compiler/ast-graph-builder.h

Index: src/compiler/ast-graph-builder.h
diff --git a/src/compiler/ast-graph-builder.h b/src/compiler/ast-graph-builder.h
index be594079ec56efb5071135a03fb18ab3699c073d..f5ad2620fc0c53c25762fc725ff4bb68c1069256 100644
--- a/src/compiler/ast-graph-builder.h
+++ b/src/compiler/ast-graph-builder.h
@@ -256,9 +256,6 @@ class AstGraphBuilder : public AstVisitor {
   // Builder to create an arguments object if it is used.
   Node* BuildArgumentsObject(Variable* arguments);
 
-  // Builder to create an array of rest parameters if used
-  Node* BuildRestArgumentsArray(Variable* rest, int index);
-
   // Builder that assigns to the {.this_function} internal variable if needed.
   Node* BuildThisFunctionVariable(Variable* this_function_var);