Implement custom element construction and some 'define' checks

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

Index: third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
diff --git a/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp b/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
index acb4cfcd292594344964e315ca59425eaed2fd62..391a19076b249945cbbde28e83e6f0102eb600ba 100644
--- a/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
+++ b/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
@@ -1322,10 +1322,12 @@ void LocalDOMWindow::cancelIdleCallback(int id)
         document->cancelIdleCallback(id);
 }
 
-CustomElementsRegistry* LocalDOMWindow::customElements() const
+CustomElementsRegistry* LocalDOMWindow::customElements(ScriptState* scriptState) const
 {
+    if (!scriptState->world().isMainWorld())
+        return nullptr;
     if (!m_customElements)
-        m_customElements = CustomElementsRegistry::create();
+        m_customElements = CustomElementsRegistry::create(scriptState, document()->registrationContext());
     return m_customElements.get();
 }