<fieldset> should be ignored in interactive validation

Source/core/html/HTMLFormElement.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, 2008, 2009 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 714 matching lines @@
     // HTMLFormControlElement::checkValidity() might change associatedElements.
     const FormAssociatedElement::List& associatedElements = this->associatedElements();
     WillBeHeapVector<RefPtrWillBeMember<FormAssociatedElement>> elements;
     elements.reserveCapacity(associatedElements.size());
     for (unsigned i = 0; i < associatedElements.size(); ++i)
         elements.append(associatedElements[i]);
     int invalidControlsCount = 0;
     for (unsigned i = 0; i < elements.size(); ++i) {
         if (elements[i]->form() == this && elements[i]->isFormControlElement()) {
             HTMLFormControlElement* control = toHTMLFormControlElement(elements[i].get());
-            if (!control->checkValidity(unhandledInvalidControls, eventBehavior) && control->formOwner() == this) {
+            if (control->isSubmittableElement() && !control->checkValidity(unhandledInvalidControls, eventBehavior) && control->formOwner() == this) {
                 ++invalidControlsCount;
                 if (!unhandledInvalidControls && eventBehavior == CheckValidityDispatchNoEvent)
                     return true;
             }
         }
     }
     return invalidControlsCount;
 }
 
 bool HTMLFormElement::reportValidity()
@@ skipping 102 matching lines @@
 }
 
 void HTMLFormElement::setDemoted(bool demoted)
 {
     if (demoted)
         UseCounter::count(document(), UseCounter::DemotedFormElement);
     m_wasDemoted = demoted;
 }
 
 } // namespace