Implement "create an element" when sync for Custom Element V1

third_party/WebKit/Source/core/dom/custom/CustomElementDefinition.h

 // 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.
 
 #ifndef CustomElementDefinition_h
 #define CustomElementDefinition_h
 
 #include "bindings/core/v8/ScriptValue.h"
 #include "core/CoreExport.h"
 #include "core/dom/custom/CustomElementDescriptor.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Noncopyable.h"
 
 namespace blink {
 
-class ScriptState;
 class Element;
+class HTMLElement;
+class QualifiedName;
 
 class CORE_EXPORT CustomElementDefinition
     : public GarbageCollectedFinalized<CustomElementDefinition> {
     WTF_MAKE_NONCOPYABLE(CustomElementDefinition);
 public:
     CustomElementDefinition(const CustomElementDescriptor&);
     virtual ~CustomElementDefinition();
 
     DECLARE_VIRTUAL_TRACE();
 
     const CustomElementDescriptor& descriptor() { return m_descriptor; }
 
     // TODO(yosin): To support Web Modules, introduce an abstract
     // class |CustomElementConstructor| to allow us to have JavaScript
     // and C++ constructors and ask the binding layer to convert
     // |CustomElementConstructor| to |ScriptValue|. Replace
     // |getConstructorForScript()| by |getConstructor() ->
     // CustomElementConstructor|.
     virtual ScriptValue getConstructorForScript() = 0;
 
     using ConstructionStack = HeapVector<Member<Element>, 1>;
     ConstructionStack& constructionStack()
     {
         return m_constructionStack;
     }
 
+    virtual HTMLElement* createCustomElement(Document&, const QualifiedName&) = 0;
+    virtual HTMLElement* createCustomElementIgnoringErrors(Document&, const QualifiedName&) = 0;
+
     void upgrade(Element*);
 
 protected:
     virtual bool runConstructor(Element*) = 0;
 
 private:
     const CustomElementDescriptor m_descriptor;
     ConstructionStack m_constructionStack;
 };
 
 } // namespace blink
 
 #endif // CustomElementDefinition_h