Custom Elements: The 'is' Attribute Should Not Be Specified on an Autonomous Custom Element

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

 // Copyright 2016 The Chromium 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 "core/dom/custom/CustomElementRegistry.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptCustomElementDefinitionBuilder.h"
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
@@ skipping 196 matching lines @@
     // e.g. |undefined| for v8.
     return ScriptValue();
   }
   return definition->getConstructorForScript();
 }
 
 // https://html.spec.whatwg.org/multipage/scripting.html#look-up-a-custom-element-definition
 // At this point, what the spec calls 'is' is 'name' from desc
 CustomElementDefinition* CustomElementRegistry::definitionFor(
     const CustomElementDescriptor& desc) const {
-  // 4&5. If there is a definition in registry with name equal to is/localName
-  // Autonomous elements have the same name and local name
-  CustomElementDefinition* definition = definitionForName(desc.name());
-  // 4&5. and name equal to localName, return that definition
-  if (definition and definition->descriptor().localName() == desc.localName())
+  // desc.name() is 'is' attribute
+  // 4. If definition in registry with name equal to local name...
+  CustomElementDefinition* definition = definitionForName(desc.localName());
+  // 5. If definition in registry with name equal to name...
+  if (!definition)
+    definition = definitionForName(desc.name());
+  // 4&5. ...and local name equal to localName, return that definition
+  if (definition and definition->descriptor().localName() == desc.localName()) {
     return definition;
+  }
   // 6. Return null
   return nullptr;
 }
 
 bool CustomElementRegistry::nameIsDefined(const AtomicString& name) const {
   return m_definitions.contains(name);
 }
 
 void CustomElementRegistry::entangle(V0CustomElementRegistrationContext* v0) {
   m_v0->add(v0);
@@ skipping 63 matching lines @@
   m_upgradeCandidates->remove(it);
 
   Document* document = m_owner->document();
   if (!document)
     return;
 
   sorter.sorted(elements, document);
 }
 
 }  // namespace blink