Expect an explicit drawOrder to be specified in a composite object, rather than relying on object key order

src/create-composite-object.js

@@ -41,7 +41,7 @@ module.exports = function createCompositeObject(options) {
 			return defaultValue(mappedProperties._, {});
 		},
 		onRender: function onRender(context) {
-			Object.keys(this.objects).forEach((objectName) => {
+			this.drawOrder.forEach((objectName) => {
 				let object = this.objects[objectName];
 				let position = getPosition(object);