Introduce toHTMLInputElement(Node*), and use it.

Source/WebKit/chromium/src/WebPageSerializer.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 49 matching lines @@
 
 namespace {
 
 KURL getSubResourceURLFromElement(Element* element)
 {
     ASSERT(element);
     const QualifiedName* attributeName = 0;
     if (element->hasTagName(HTMLNames::imgTag) || element->hasTagName(HTMLNames::scriptTag))
         attributeName = &HTMLNames::srcAttr;
     else if (element->hasTagName(HTMLNames::inputTag)) {
-        HTMLInputElement* input = static_cast<HTMLInputElement*>(element);
-        if (input->isImageButton())
+        if (toHTMLInputElement(element)->isImageButton())
             attributeName = &HTMLNames::srcAttr;
     } else if (element->hasTagName(HTMLNames::bodyTag)
                || element->hasTagName(HTMLNames::tableTag)
                || element->hasTagName(HTMLNames::trTag)
                || element->hasTagName(HTMLNames::tdTag))
         attributeName = &HTMLNames::backgroundAttr;
     else if (element->hasTagName(HTMLNames::blockquoteTag)
              || element->hasTagName(HTMLNames::qTag)
              || element->hasTagName(HTMLNames::delTag)
              || element->hasTagName(HTMLNames::insTag))
@@ skipping 211 matching lines @@
 
 WebString WebPageSerializer::generateBaseTagDeclaration(const WebString& baseTarget)
 {
     if (baseTarget.isEmpty())
         return String(ASCIILiteral("<base href=\".\">"));
     String baseString = "<base href=\".\" target=\"" + static_cast<const String&>(baseTarget) + "\">";
     return baseString;
 }
 
 } // namespace WebKit