[cleanup] Remove cruft from old rest parameter implementation

src/ast/scopes.cc

Index: src/ast/scopes.cc
diff --git a/src/ast/scopes.cc b/src/ast/scopes.cc
index 1eb5b66a9377df597dca77325581b715479281c1..2f473a68428b7f7f51958af25851c8d8adce6159 100644
--- a/src/ast/scopes.cc
+++ b/src/ast/scopes.cc
@@ -207,7 +207,6 @@ void Scope::SetDefaults(ScopeType scope_type, Scope* outer_scope,
   arity_ = 0;
   has_simple_parameters_ = true;
   rest_parameter_ = NULL;
-  rest_index_ = -1;
   scope_info_ = scope_info;
   start_position_ = RelocInfo::kNoPosition;
   end_position_ = RelocInfo::kNoPosition;
@@ -528,7 +527,6 @@ Variable* Scope::DeclareParameter(
   if (is_rest) {
     DCHECK_NULL(rest_parameter_);
     rest_parameter_ = var;
-    rest_index_ = num_parameters();
   }
   params_.Add(var, zone());
   return var;