Have ElementTraversal::firstWithin() take a reference

Source/core/dom/TreeScope.cpp

 /*
  * Copyright (C) 2011 Google Inc. All Rights Reserved.
  * Copyright (C) 2012 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 259 matching lines @@
 }
 
 HTMLLabelElement* TreeScope::labelElementForId(const AtomicString& forAttributeValue)
 {
     if (forAttributeValue.isEmpty())
         return 0;
 
     if (!m_labelsByForAttribute) {
         // Populate the map on first access.
         m_labelsByForAttribute = adoptPtr(new DocumentOrderedMap);
-        for (Element* element = ElementTraversal::firstWithin(rootNode()); element; element = ElementTraversal::next(*element)) {
+        ASSERT(rootNode());
+        for (Element* element = ElementTraversal::firstWithin(*rootNode()); element; element = ElementTraversal::next(*element)) {
             if (isHTMLLabelElement(element)) {
                 HTMLLabelElement* label = toHTMLLabelElement(element);
                 const AtomicString& forValue = label->fastGetAttribute(forAttr);
                 if (!forValue.isEmpty())
                     addLabel(forValue, label);
             }
         }
     }
 
     return toHTMLLabelElement(m_labelsByForAttribute->getElementByLabelForAttribute(forAttributeValue.impl(), this));
@@ skipping 13 matching lines @@
     m_selection = DOMSelection::create(this);
     return m_selection.get();
 }
 
 Element* TreeScope::findAnchor(const String& name)
 {
     if (name.isEmpty())
         return 0;
     if (Element* element = getElementById(name))
         return element;
-    for (Element* element = ElementTraversal::firstWithin(rootNode()); element; element = ElementTraversal::next(*element)) {
+    ASSERT(rootNode());
+    for (Element* element = ElementTraversal::firstWithin(*rootNode()); element; element = ElementTraversal::next(*element)) {
         if (isHTMLAnchorElement(element)) {
             HTMLAnchorElement* anchor = toHTMLAnchorElement(element);
             if (rootNode()->document().inQuirksMode()) {
                 // Quirks mode, case insensitive comparison of names.
                 if (equalIgnoringCase(anchor->name(), name))
                     return anchor;
             } else {
                 // Strict mode, names need to match exactly.
                 if (anchor->name() == name)
                     return anchor;
@@ skipping 153 matching lines @@
     }
     return false;
 }
 
 Element* TreeScope::getElementByAccessKey(const String& key) const
 {
     if (key.isEmpty())
         return 0;
     Element* result = 0;
     Node* root = rootNode();
-    for (Element* element = ElementTraversal::firstWithin(root); element; element = ElementTraversal::next(*element, root)) {
+    ASSERT(root);
+    for (Element* element = ElementTraversal::firstWithin(*root); element; element = ElementTraversal::next(*element, root)) {
         if (equalIgnoringCase(element->fastGetAttribute(accesskeyAttr), key))
             result = element;
         for (ShadowRoot* shadowRoot = element->youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot()) {
             if (Element* shadowResult = shadowRoot->getElementByAccessKey(key))
                 result = shadowResult;
         }
     }
     return result;
 }
 
 } // namespace WebCore