Make RenderObject::style() return a const object

Source/web/WebFormControlElement.cpp

 /*
  * Copyright (C) 2010 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 147 matching lines @@
 {
     if (isHTMLInputElement(*m_private))
         return constUnwrap<HTMLInputElement>()->selectionEnd();
     if (isHTMLTextAreaElement(*m_private))
         return constUnwrap<HTMLTextAreaElement>()->selectionEnd();
     return 0;
 }
 
 WebString WebFormControlElement::directionForFormData() const
 {
-    if (LayoutStyle* style = constUnwrap<HTMLFormControlElement>()->layoutStyle())
+    if (const LayoutStyle* style = constUnwrap<HTMLFormControlElement>()->layoutStyle())
         return style->isLeftToRightDirection() ? WebString::fromUTF8("ltr") : WebString::fromUTF8("rtl");
     return WebString::fromUTF8("ltr");
 }
 
 bool WebFormControlElement::isActivatedSubmit() const
 {
     return constUnwrap<HTMLFormControlElement>()->isActivatedSubmit();
 }
 
 WebFormElement WebFormControlElement::form() const
@@ skipping 11 matching lines @@
     m_private = elem;
     return *this;
 }
 
 WebFormControlElement::operator PassRefPtrWillBeRawPtr<HTMLFormControlElement>() const
 {
     return toHTMLFormControlElement(m_private.get());
 }
 
 } // namespace blink