Add clear() to Element.classList.

sky/engine/core/dom/DOMTokenList.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:
  * 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
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 65 matching lines @@
 const AtomicString& DOMTokenList::value() const
 {
     return m_element->getAttribute(HTMLNames::classAttr);
 }
 
 void DOMTokenList::setValue(const AtomicString& value)
 {
     m_element->setAttribute(HTMLNames::classAttr, value);
 }
 
+void DOMTokenList::clear()
+{
+    m_element->removeAttribute(HTMLNames::classAttr);
+}
+
 bool DOMTokenList::validateToken(const String& token, ExceptionState& exceptionState)
 {
     if (token.isEmpty()) {
         exceptionState.throwDOMException(SyntaxError, "The token provided must not be empty.");
         return false;
     }
 
     if (token.find(isHTMLSpace) != kNotFound) {
         exceptionState.throwDOMException(InvalidCharacterError, "The token provided ('" + token + "') contains HTML space characters, which are not valid in tokens.");
         return false;
@@ skipping 195 matching lines @@
                 output.append(' ');
         } else {
             output.append(token); // Step 9
         }
     }
 
     return output.toAtomicString();
 }
 
 } // namespace blink