The HTML parser synchronously creates custom elements

third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 1310 matching lines @@
 CustomElementsRegistry* LocalDOMWindow::customElements(ScriptState* scriptState) const
 {
     if (!scriptState->world().isMainWorld())
         return nullptr;
     return customElements();
 }
 
 CustomElementsRegistry* LocalDOMWindow::customElements() const
 {
     if (!m_customElements && m_document)
-        m_customElements = CustomElementsRegistry::create(document());
+        m_customElements = CustomElementsRegistry::create(this);
     return m_customElements;
 }
 
+CustomElementsRegistry* LocalDOMWindow::maybeCustomElements() const
+{
+    return m_customElements;
+}
+
 void LocalDOMWindow::addedEventListener(const AtomicString& eventType, RegisteredEventListener& registeredListener)
 {
     DOMWindow::addedEventListener(eventType, registeredListener);
     if (frame() && frame()->host())
         frame()->host()->eventHandlerRegistry().didAddEventHandler(*this, eventType, registeredListener.options());
 
     if (Document* document = this->document())
         document->addListenerTypeIfNeeded(eventType);
 
     for (auto& it : m_eventListenerObservers) {
@@ skipping 192 matching lines @@
 {
     // If the LocalDOMWindow still has a frame reference, that frame must point
     // back to this LocalDOMWindow: otherwise, it's easy to get into a situation
     // where script execution leaks between different LocalDOMWindows.
     if (m_frameObserver->frame())
         ASSERT_WITH_SECURITY_IMPLICATION(m_frameObserver->frame()->domWindow() == this);
     return m_frameObserver->frame();
 }
 
 } // namespace blink