Optimize usage of redundant method calls in layout classes

There are a bunch of places in layout classes where redundant method calls are being made, such as in AnchorPane layoutChildren as seen below:


        for (int i = 0; i < getChildren().size(); i++) {
            Node child = getChildren().get(i);
            ...
        }


This will likely have very little impact, but it is a minor thing worth doing and easy to do.