Introduce toHTMLInputElement(Node*), and use it.

Source/core/html/HTMLFormControlElement.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 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 166 matching lines @@
         // FIXME: This message should be moved off the console once a solution to https://bugs.webkit.org/show_bug.cgi?id=103274 exists.
         element->document()->addConsoleMessage(SecurityMessageSource, ErrorMessageLevel, "Blocked autofocusing on a form control because the form's frame is sandboxed and the 'allow-scripts' permission is not set.");
         return false;
     }
     if (element->hasAutofocused())
         return false;
 
     // FIXME: Should this set of hasTagName checks be replaced by a
     // virtual member function?
     if (element->hasTagName(inputTag))
-        return !static_cast<HTMLInputElement*>(element)->isInputTypeHidden();
+        return !toHTMLInputElement(element)->isInputTypeHidden();
     if (element->hasTagName(selectTag))
         return true;
     if (element->hasTagName(keygenTag))
         return true;
     if (element->hasTagName(buttonTag))
         return true;
     if (element->hasTagName(textareaTag))
         return true;
 
     return false;
@@ skipping 275 matching lines @@
 }
 
 void HTMLFormControlElement::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
 {
     MemoryClassInfo info(memoryObjectInfo, this, WebCoreMemoryTypes::DOM);
     LabelableElement::reportMemoryUsage(memoryObjectInfo);
     info.addMember(m_validationMessage, "validationMessage");
 }
 
 } // namespace Webcore