Use more references in ContainerNode code

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 2990 matching lines @@
         // Documents may contain no more than one of each of these.
         // (One Element and one DocumentType.)
         for (Node* c = firstChild(); c; c = c->nextSibling())
             if (c->nodeType() == type)
                 return false;
         return true;
     }
     return false;
 }
 
-bool Document::canReplaceChild(Node* newChild, Node* oldChild)
+bool Document::canReplaceChild(Node& newChild, Node& oldChild)
 {
-    if (!oldChild)
-        // ContainerNode::replaceChild will raise a NotFoundError.
-        return true;
-
-    if (oldChild->nodeType() == newChild->nodeType())
+    if (oldChild.nodeType() == newChild.nodeType())
         return true;
 
     int numDoctypes = 0;
     int numElements = 0;
 
     // First, check how many doctypes and elements we have, not counting
     // the child we're about to remove.
     for (Node* c = firstChild(); c; c = c->nextSibling()) {
         if (c == oldChild)
             continue;
 
         switch (c->nodeType()) {
         case DOCUMENT_TYPE_NODE:
             numDoctypes++;
             break;
         case ELEMENT_NODE:
             numElements++;
             break;
         default:
             break;
         }
     }
 
     // Then, see how many doctypes and elements might be added by the new child.
-    if (newChild->nodeType() == DOCUMENT_FRAGMENT_NODE) {
-        for (Node* c = newChild->firstChild(); c; c = c->nextSibling()) {
+    if (newChild.nodeType() == DOCUMENT_FRAGMENT_NODE) {
+        for (Node* c = newChild.firstChild(); c; c = c->nextSibling()) {
             switch (c->nodeType()) {
             case ATTRIBUTE_NODE:
             case CDATA_SECTION_NODE:
             case DOCUMENT_FRAGMENT_NODE:
             case DOCUMENT_NODE:
             case ENTITY_NODE:
             case NOTATION_NODE:
             case TEXT_NODE:
             case XPATH_NAMESPACE_NODE:
                 return false;
             case COMMENT_NODE:
             case PROCESSING_INSTRUCTION_NODE:
                 break;
             case DOCUMENT_TYPE_NODE:
                 numDoctypes++;
                 break;
             case ELEMENT_NODE:
                 numElements++;
                 break;
             }
         }
     } else {
-        switch (newChild->nodeType()) {
+        switch (newChild.nodeType()) {
         case ATTRIBUTE_NODE:
         case CDATA_SECTION_NODE:
         case DOCUMENT_FRAGMENT_NODE:
         case DOCUMENT_NODE:
         case ENTITY_NODE:
         case NOTATION_NODE:
         case TEXT_NODE:
         case XPATH_NAMESPACE_NODE:
             return false;
         case COMMENT_NODE:
@@ skipping 2136 matching lines @@
 void Document::modifiedStyleSheet(StyleSheet* sheet, RecalcStyleTime when, StyleResolverUpdateMode updateMode)
 {
     if (!isActive())
         return;
 
     styleEngine()->modifiedStyleSheet(sheet);
     styleResolverChanged(when, updateMode);
 }
 
 } // namespace WebCore