Introduce toHTMLInputElement(Node*), and use it.

Source/WebKit/chromium/src/EditorClientImpl.cpp

 /*
  * Copyright (C) 2006, 2007 Apple, Inc.  All rights reserved.
  * Copyright (C) 2012 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 602 matching lines @@
 
     // Notification that focus was lost.  Be careful with this, it's also sent
     // when the page is being closed.
 
     // Hide any showing popup.
     m_webView->hideAutofillPopup();
 }
 
 void EditorClientImpl::textDidChangeInTextField(Element* element)
 {
-    ASSERT(element->hasLocalName(HTMLNames::inputTag));
-    HTMLInputElement* inputElement = static_cast<HTMLInputElement*>(element);
+    HTMLInputElement* inputElement = toHTMLInputElement(element);
     if (m_webView->autofillClient())
         m_webView->autofillClient()->textFieldDidChange(WebInputElement(inputElement));
 }
 
 bool EditorClientImpl::doTextFieldCommandFromEvent(Element* element,
                                                    KeyboardEvent* event)
 {
     HTMLInputElement* inputElement = element->toInputElement();
     if (m_webView->autofillClient() && inputElement) {
         m_webView->autofillClient()->textFieldDidReceiveKeyDown(WebInputElement(inputElement),
@@ skipping 127 matching lines @@
 #endif
 }
 
 void EditorClientImpl::willSetInputMethodState()
 {
     if (m_webView->client())
         m_webView->client()->resetInputMethod();
 }
 
 } // namesace WebKit