If 'is' is not null and custom element definition not found, NotFoundError should be thrown

third_party/WebKit/Source/core/dom/custom/V0CustomElementRegistrationContext.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * 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 159 matching lines @@
 bool V0CustomElementRegistrationContext::nameIsDefined(
     const AtomicString& name) const {
   return m_registry.nameIsDefined(name);
 }
 
 void V0CustomElementRegistrationContext::setV1(
     const CustomElementRegistry* v1) {
   m_registry.setV1(v1);
 }
 
+bool V0CustomElementRegistrationContext::v1NameIsDefined(
+    const AtomicString& name) const {
+  return m_registry.v1NameIsDefined(name);
+}
+
 DEFINE_TRACE(V0CustomElementRegistrationContext) {
   visitor->trace(m_candidates);
   visitor->trace(m_registry);
 }
 
 }  // namespace blink