Put Scopes into temporary Zone

src/ast/ast.cc

Index: src/ast/ast.cc
diff --git a/src/ast/ast.cc b/src/ast/ast.cc
index a2fc8997a4a07be151afd82ac4c6de0016c762e7..3c4d300a478d513faccccd90613b7e52a1dad558 100644
--- a/src/ast/ast.cc
+++ b/src/ast/ast.cc
@@ -204,6 +204,18 @@ VariableProxy::VariableProxy(Zone* zone, const AstRawString* name,
       raw_name_(name),
       next_unresolved_(nullptr) {}
 
+VariableProxy::VariableProxy(Zone* zone, const VariableProxy* clone_from)
+    : Expression(zone, clone_from->position(), kVariableProxy),
+      bit_field_(clone_from->bit_field_),
+      end_position_(clone_from->end_position_),
+      next_unresolved_(nullptr) {
+  if (clone_from->is_resolved()) {
+    var_ = clone_from->var_;
+  } else {
+    raw_name_ = clone_from->raw_name_;
+  }
+}
+
 void VariableProxy::BindTo(Variable* var) {
   DCHECK((is_this() && var->is_this()) || raw_name() == var->raw_name());
   set_var(var);