Introduce toHTMLInputElement(Node*), and use it.

Source/core/accessibility/AccessibilityMediaControls.cpp

 /*
  * Copyright (C) 2009 Apple 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 253 matching lines @@
 {
     return adoptRef(new AccessibilityMediaTimeline(renderer));
 }
 
 String AccessibilityMediaTimeline::valueDescription() const
 {
     Node* node = m_renderer->node();
     if (!node->hasTagName(inputTag))
         return String();
 
-    float time = static_cast<HTMLInputElement*>(node)->value().toFloat();
-    return localizedMediaTimeDescription(time);
+    return localizedMediaTimeDescription(toHTMLInputElement(node)->value().toFloat());
 }
 
 String AccessibilityMediaTimeline::helpText() const
 {
     DEFINE_STATIC_LOCAL(const String, slider, (ASCIILiteral("Slider")));
     return localizedMediaControlElementHelpText(slider);
 }
 
 
 //
@@ skipping 35 matching lines @@
 {
     if (!m_renderer || !m_renderer->node())
         return String();
 
     MediaControlTimeDisplayElement* element = static_cast<MediaControlTimeDisplayElement*>(m_renderer->node());
     float time = element->currentValue();
     return localizedMediaTimeDescription(fabsf(time));
 }
 
 } // namespace WebCore