[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 201a20a18afec5c011bb5abbabcef55e1354d4d6..766b96ff9e3c59ee06f2313baa2e6774025ecaac 100644
--- a/src/compiler/ast-graph-builder.h
+++ b/src/compiler/ast-graph-builder.h
@@ -262,9 +262,6 @@ 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);