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

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 1b58988fa57f7919eb3c223be714fb8e9d4aa15d..0958eb4485e22fb1e37254802ae491be0a8d193e 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -3333,8 +3333,8 @@ bool Document::canReplaceChild(const Node& newChild, const Node& oldChild) const
     }
 
     // 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: