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

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

Index: third_party/WebKit/Source/core/dom/custom/CustomElement.h
diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElement.h b/third_party/WebKit/Source/core/dom/custom/CustomElement.h
index d86f22d3e64861bbb31a5407aafe19722652e4e2..b4637109016095e548aa896aefdf71e9aaad1d7d 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElement.h
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElement.h
@@ -27,6 +27,7 @@ public:
     // may be a different object for a given element over its lifetime
     // as it moves between documents.
     static CustomElementsRegistry* registry(const Element&);
+    static CustomElementsRegistry* registry(const Document&);
 
     // Returns true if element could possibly match a custom element
     // descriptor *now*. See CustomElementDescriptor::matches for the
@@ -57,6 +58,9 @@ public:
     static HTMLElement* createCustomElement(Document&, const QualifiedName&, CreateElementFlags);
 
     static void enqueueUpgradeReaction(Element*, CustomElementDefinition*);
+
+private:
+    static HTMLElement* createCustomElementAsync(Document&, CustomElementDefinition&, const QualifiedName&);
 };
 
 } // namespace blink