Merge pull request preactjs#697 from bmeurer/Load_VNode_nodeName_only_once

Load vnode.nodeName only once.

Author: robertknight

src/vdom/diff.js

@@ -94,18 +94,20 @@ function idiff(dom, vnode, context, mountAll, componentRoot) {
 
 
 	// If the VNode represents a Component, perform a component diff:
-	if (typeof vnode.nodeName==='function') {
+	let vnodeName = vnode.nodeName;
+	if (typeof vnodeName==='function') {
 		return buildComponentFromVNode(dom, vnode, context, mountAll);
 	}
 
 
 	// Tracks entering and exiting SVG namespace when descending through the tree.
-	isSvgMode = vnode.nodeName==='svg' ? true : vnode.nodeName==='foreignObject' ? false : isSvgMode;
+	isSvgMode = vnodeName==='svg' ? true : vnodeName==='foreignObject' ? false : isSvgMode;
 
 
 	// If there's no existing element or it's the wrong type, create a new one:
-	if (!dom || !isNamedNode(dom, String(vnode.nodeName))) {
-		out = createNode(String(vnode.nodeName), isSvgMode);
+	vnodeName = String(vnodeName);
+	if (!dom || !isNamedNode(dom, vnodeName)) {
+		out = createNode(vnodeName, isSvgMode);
 
 		if (dom) {
 			// move children into the replacement node