[es6] Re-implement rest parameters via desugaring.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 794a38b8e4d4faa0f703c5e520fdc69e6c734e60..ed8b45c2af15e7fd2f0508ac92ade16387598390 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -4723,12 +4723,6 @@ void HOptimizedGraphBuilder::SetUpScope(Scope* scope) {
                         graph()->GetArgumentsObject());
   }
 
-  int rest_index;
-  Variable* rest = scope->rest_parameter(&rest_index);
-  if (rest) {
-    return Bailout(kRestParameter);
-  }
-
   if (scope->this_function_var() != nullptr ||
       scope->new_target_var() != nullptr) {
     return Bailout(kSuperReference);