Do not ignore an empty context with extension when creating a scope object.

src/scopes.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 131 matching lines @@
       inner_scopes_(4),
       variables_(),
       temps_(4),
       params_(4),
       unresolved_(16),
       decls_(4),
       already_resolved_(true) {
   SetDefaults(type, NULL, scope_info);
   if (!scope_info.is_null()) {
     num_heap_slots_ = scope_info_->ContextLength();
-    if (*scope_info != ScopeInfo::Empty()) {
-      language_mode_ = scope_info->language_mode();
-    }
-  } else if (is_with_scope()) {
-    num_heap_slots_ = Context::MIN_CONTEXT_SLOTS;
   }
+  // Ensure at least MIN_CONTEXT_SLOTS to indicate a materialized context.
+  num_heap_slots_ = Max(num_heap_slots_,
+                        static_cast<int>(Context::MIN_CONTEXT_SLOTS));
   AddInnerScope(inner_scope);
 }
 
 
 Scope::Scope(Scope* inner_scope, Handle<String> catch_variable_name)
     : isolate_(Isolate::Current()),
       inner_scopes_(1),
       variables_(),
       temps_(0),
       params_(0),
@@ skipping 1062 matching lines @@
 }
 
 
 int Scope::ContextLocalCount() const {
   if (num_heap_slots() == 0) return 0;
   return num_heap_slots() - Context::MIN_CONTEXT_SLOTS -
       (function_ != NULL && function_->var()->IsContextSlot() ? 1 : 0);
 }
 
 } }  // namespace v8::internal