SceneUtils: Minor tweak.

src/extras/SceneUtils.js

@@ -6,7 +6,7 @@ THREE.SceneUtils = {
 
 	createMultiMaterialObject: function ( geometry, materials ) {
 
-		var group = new THREE.Object3D();
+		var group = new THREE.Group();
 
 		for ( var i = 0, l = materials.length; i < l; i ++ ) {