<marquee> in <template> should not crash

Source/core/html/HTMLMarqueeElement.h

Index: Source/core/html/HTMLMarqueeElement.h
diff --git a/Source/core/html/HTMLMarqueeElement.h b/Source/core/html/HTMLMarqueeElement.h
index 083380a8a1379b5fd4e104d799fe40e663880238..3776c30d95d1ae5beb2428a98ef5677cde020e73 100644
--- a/Source/core/html/HTMLMarqueeElement.h
+++ b/Source/core/html/HTMLMarqueeElement.h
@@ -34,10 +34,15 @@ public:
 
     virtual void attributeWillChange(const QualifiedName&, const AtomicString& oldValue, const AtomicString& newValue) final;
     virtual InsertionNotificationRequest insertedInto(ContainerNode*) final;
+    virtual void didNotifySubtreeInsertionsToDocument() final;
     virtual void removedFrom(ContainerNode*) final;
 
+    void callCreatedCallbackIfNeeded();
+
 private:
     explicit HTMLMarqueeElement(Document&);
+
+    bool m_didCallCreatedCallback;
 };
 
 } // namespace blink