fix out-of-order issue when mixing new and old elements

tests/mithril-tests.js

@@ -142,13 +142,14 @@ function testMithril(mock) {
 		return root.childNodes[0].childNodes[0].childNodes[0].nodeName === "A"
 	})
 	test(function() {
+		//https://github.com/lhorie/mithril.js/issues/43
 		var root = mock.document.createElement("div")
 		m.render(root, m("a", {config: m.route}, "test"))
 		m.render(root, m("a", {config: m.route}, "test"))
 		return root.childNodes[0].childNodes[0].nodeValue === "test"
 	})
 	test(function() {
-		//see issue #29
+		//https://github.com/lhorie/mithril.js/issues/29
 		var root = mock.document.createElement("div")
 		var list = [false, false]
 		m.render(root, list.reverse().map(function(flag, index) {
@@ -167,6 +168,20 @@ function testMithril(mock) {
 		
 		return root.childNodes[0].checked === false && root.childNodes[1].checked === true
 	})
+	test(function() {
+		//https://github.com/lhorie/mithril.js/issues/44
+		var root = mock.document.createElement("div")
+		m.render(root, m("#foo", [null, m("#bar")]))
+		m.render(root, m("#foo", ["test", m("#bar")]))
+		return root.childNodes[0].childNodes[0].nodeValue === "test"
+	})
+	test(function() {
+		//https://github.com/lhorie/mithril.js/issues/44
+		var root = mock.document.createElement("div")
+		m.render(root, m("#foo", [null, m("#bar")]))
+		m.render(root, m("#foo", [m("div"), m("#bar")]))
+		return root.childNodes[0].childNodes[0].nodeName === "DIV"
+	})
 	
 	//m.redraw
 	test(function() {

tests/mock.js

@@ -10,6 +10,12 @@ mock.window = new function() {
 			appendChild: window.document.appendChild,
 			removeChild: window.document.removeChild,
 			replaceChild: window.document.replaceChild,
+			insertBefore: function(node, reference) {
+				node.parentNode = this
+				var index = this.childNodes.indexOf(reference)
+				if (index < 0) this.childNodes.push(node)
+				else this.childNodes.splice(index, 0, node)
+			},
 			setAttribute: function(name, value) {
 				this[name] = value.toString()
 			},