Option, checkbox and radio should support ':default' selector

third_party/WebKit/Source/core/html/HTMLButtonElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2010 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2007 Samuel Weinig (sam@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 196 matching lines @@
 bool HTMLButtonElement::isInteractiveContent() const
 {
     return true;
 }
 
 bool HTMLButtonElement::supportsAutofocus() const
 {
     return true;
 }
 
+bool HTMLButtonElement::matchesDefaultPseudoClass() const
+{
+    // HTMLFormElement::findDefaultButton() traverses the tree. So we check
+    // canBeSuccessfulSubmitButton() first for early return.
+    return canBeSuccessfulSubmitButton() && form() && form()->findDefaultButton() == this;
+}
+
 Node::InsertionNotificationRequest HTMLButtonElement::insertedInto(ContainerNode* insertionPoint)
 {
     InsertionNotificationRequest request = HTMLFormControlElement::insertedInto(insertionPoint);
     logAddElementIfIsolatedWorldAndInDocument("button", typeAttr, formmethodAttr, formactionAttr);
     return request;
 }
 
 } // namespace blink