Minimize calls to Node::nodeType() as it is virtual

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 3315 matching lines @@
             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.isDocumentFragment()) {
+        for (Node* c = toDocumentFragment(newChild).firstChild(); c; c = c->nextSibling()) {

[aandrey, 2014/06/02 14:50:51]

why change this?

[Inactive, 2014/06/02 15:48:02]

Because this ends up calling ContainerNode::firstChild() instead of
Node::firstChild(). This is faster because it bypasses the useless
isContainerNode() check.

[Inactive, 2014/06/02 15:49:02]

BTW, this is not the only place where we should do this. I have a follow-up
patch to do this in other places as well.

             switch (c->nodeType()) {
             case ATTRIBUTE_NODE:
             case CDATA_SECTION_NODE:
             case DOCUMENT_FRAGMENT_NODE:
             case DOCUMENT_NODE:
             case TEXT_NODE:
                 return false;
             case COMMENT_NODE:
             case PROCESSING_INSTRUCTION_NODE:
                 break;
@@ skipping 2454 matching lines @@
     visitor->trace(m_timeline);
     visitor->trace(m_compositorPendingAnimations);
     visitor->registerWeakMembers<Document, &Document::clearWeakMembers>(this);
     DocumentSupplementable::trace(visitor);
     TreeScope::trace(visitor);
     ContainerNode::trace(visitor);
     ExecutionContext::trace(visitor);
 }
 
 } // namespace WebCore