new classes: special construct stub for derived classs and TDZ for `this`.

src/scopes.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/scopes.h"
 
 #include "src/accessors.h"
 #include "src/bootstrapper.h"
@@ skipping 273 matching lines @@
     PrintF("global : ");
     top->interface()->Print();
   }
 #endif
 
   info->PrepareForCompilation(scope);
   return true;
 }
 
 
-void Scope::Initialize() {
+void Scope::Initialize(bool uninitialized_this) {
   DCHECK(!already_resolved());
 
   // Add this scope as a new inner scope of the outer scope.
   if (outer_scope_ != NULL) {
     outer_scope_->inner_scopes_.Add(this, zone());
     scope_inside_with_ = outer_scope_->scope_inside_with_ || is_with_scope();
   } else {
     scope_inside_with_ = is_with_scope();
   }
 
   // Declare convenience variables.
   // Declare and allocate receiver (even for the script scope, and even
   // if naccesses_ == 0).
   // NOTE: When loading parameters in the script scope, we must take
   // care not to access them as properties of the global object, but
   // instead load them directly from the stack. Currently, the only
   // such parameter is 'this' which is passed on the stack when
   // invoking scripts
   if (is_declaration_scope()) {
-    Variable* var =
-        variables_.Declare(this,
-                           ast_value_factory_->this_string(),
-                           VAR,
-                           false,
-                           Variable::THIS,
-                           kCreatedInitialized);
+    DCHECK(!uninitialized_this || is_function_scope());
+    DCHECK(FLAG_experimental_classes || !uninitialized_this);
+    Variable* var = variables_.Declare(
+        this, ast_value_factory_->this_string(),
+        uninitialized_this ? CONST : VAR, false, Variable::THIS,
+        uninitialized_this ? kNeedsInitialization : kCreatedInitialized);
     var->AllocateTo(Variable::PARAMETER, -1);
     receiver_ = var;
   } else {
     DCHECK(outer_scope() != NULL);
     receiver_ = outer_scope()->receiver();
   }
 
   if (is_function_scope()) {
     // Declare 'arguments' variable which exists in all functions.
     // Note that it might never be accessed, in which case it won't be
@@ skipping 1108 matching lines @@
 }
 
 
 int Scope::ContextLocalCount() const {
   if (num_heap_slots() == 0) return 0;
   return num_heap_slots() - Context::MIN_CONTEXT_SLOTS -
       (function_ != NULL && function_->proxy()->var()->IsContextSlot() ? 1 : 0);
 }
 
 } }  // namespace v8::internal