Make the benchmark a little more precise

We special-case identical vnode trees, so it's better that we test both
identical and rebuilt trees when benchmarking rendering.

performance/test-perf.js

@@ -70,7 +70,7 @@ suite.on("complete", function() {
 suite.on("error", console.error.bind(console))
 
 suite.add({
-	name : "rerender without changes",
+	name : "rerender identical vnode",
 	onStart : function() {
 		this.vdom = m("div", {class: "foo bar", "data-foo": "bar", p: 2},
 			m("header",
@@ -119,6 +119,53 @@ suite.add({
 	}
 })
 
+suite.add({
+	name : "rerender same tree",
+	fn : function() {
+		m.render(scratch, m("div", {class: "foo bar", "data-foo": "bar", p: 2},
+			m("header",
+				m("h1", {class: "asdf"}, "a ", "b", " c ", 0, " d"),
+				m("nav",
+					m("a", {href: "/foo"}, "Foo"),
+					m("a", {href: "/bar"}, "Bar")
+				)
+			),
+			m("main",
+				m("form", {onSubmit: function onSubmit() {}},
+					m("input", {type: "checkbox", checked: true}),
+					m("input", {type: "checkbox", checked: false}),
+					m("fieldset",
+						m("label",
+							m("input", {type: "radio", checked: true})
+						),
+						m("label",
+							m("input", {type: "radio"})
+						)
+					),
+					m("button-bar",
+						m("button",
+							{style: "width:10px; height:10px; border:1px solid #FFF;"},
+							"Normal CSS"
+						),
+						m("button",
+							{style: "top:0 ; right: 20"},
+							"Poor CSS"
+						),
+						m("button",
+							{style: "invalid-prop:1;padding:1px;font:12px/1.1 arial,sans-serif;", icon: true},
+							"Poorer CSS"
+						),
+						m("button",
+							{style: {margin: 0, padding: "10px", overflow: "visible"}},
+							"Object CSS"
+						)
+					)
+				)
+			)
+		))
+	}
+})
+
 suite.add({
 	name : "construct large VDOM tree",