Filter out synthetic variables from with scopes

src/ast/scopes.cc

Index: src/ast/scopes.cc
diff --git a/src/ast/scopes.cc b/src/ast/scopes.cc
index d45b02091cd805d1b0e5ec8fad07f651cac2ca7b..0b35d412172ccefeb7efaddd182209d3aff82bbf 100644
--- a/src/ast/scopes.cc
+++ b/src/ast/scopes.cc
@@ -1446,7 +1446,7 @@ Variable* Scope::LookupRecursive(VariableProxy* proxy, bool declare_free,
   // "this" can't be shadowed by "eval"-introduced bindings or by "with"
   // scopes.
   // TODO(wingo): There are other variables in this category; add them.
-  if (var->is_this()) return var;
+  if (ScopeInfo::VariableIsSynthetic(*var->name())) return var;
 
   if (is_with_scope()) {
     // The current scope is a with scope, so the variable binding can not be