Make Element::attributes() less error-prone and simplify call sites

Source/core/html/parser/HTMLConstructionSite.cpp

 /*
  * Copyright (C) 2010 Google, Inc. All Rights Reserved.
  * Copyright (C) 2011 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 389 matching lines @@
     dispatchDocumentElementAvailableIfNeeded();
 }
 
 void HTMLConstructionSite::mergeAttributesFromTokenIntoElement(AtomicHTMLToken* token, Element* element)
 {
     if (token->attributes().isEmpty())
         return;
 
     for (unsigned i = 0; i < token->attributes().size(); ++i) {
         const Attribute& tokenAttribute = token->attributes().at(i);
-        if (!element->elementData() || element->attributes().findIndex(tokenAttribute.name()) == kNotFound)
+        if (element->attributesWithoutUpdate().findIndex(tokenAttribute.name()) == kNotFound)
             element->setAttribute(tokenAttribute.name(), tokenAttribute.value());
     }
 }
 
 void HTMLConstructionSite::insertHTMLHtmlStartTagInBody(AtomicHTMLToken* token)
 {
     // Fragments do not have a root HTML element, so any additional HTML elements
     // encountered during fragment parsing should be ignored.
     if (m_isParsingFragment)
         return;
@@ skipping 448 matching lines @@
 }
 
 void HTMLConstructionSite::PendingText::trace(Visitor* visitor)
 {
     visitor->trace(parent);
     visitor->trace(nextChild);
 }
 
 
 }