Implement custom element construction and some 'define' checks

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 1306 matching lines @@
 }
 
 void LocalDOMWindow::cancelIdleCallback(int id)
 {
     if (Document* document = this->document())
         document->cancelIdleCallback(id);
 }
 
 CustomElementsRegistry* LocalDOMWindow::customElements() const
 {
-    if (!m_customElements)
-        m_customElements = CustomElementsRegistry::create();
+    if (!m_customElements && frame()) {
+        ScriptState* scriptState = ScriptState::forMainWorld(frame());

[haraken, 2016/05/10 09:04:22]

Can you add [CallWith=ScriptState] to Window.customElements and pass in the
ScriptState from the binding layer?

[dominicc (has gone to gerrit), 2016/05/11 02:31:49]

We actually really need to construct that object in the main world; I put some
details in a reply to CustomElementsRegistry. It's about the map that object
maintains needs to be in the main world isolate.

[haraken, 2016/05/11 06:25:28]

It's nasty to manipulate V8 objects in a different world... (It has a risk of
leaking wrappers between worlds.)

Would it be an option to simply disallow the isolated world to access
customElements until you implement per-world CustomElementsRegistry correctly?

+        m_customElements = CustomElementsRegistry::create(scriptState);
+    }
     return m_customElements.get();
 }
 
 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())
@@ skipping 189 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