StyleHelper.transitionToState doesn't properly handle CSS key lists containing multiple Type.FONT keys

While chasing down a problem where changes to the .scene -fx-font
was not resulting in a change in the font size of sliders with labeled
tick marks, I ran into a bit of code in StyleHelper.transitionToState that
does this:

        // First we want to lookup the font associated with the Node in its
        // current state so that all subsequent font-related sizes will be
        // correct.
        def keys:Key[] = node.impl_cssKeys();
        var fontKey = DEFAULT_FONT_KEY;
        for (key in keys) {
            if (key.type == Type.FONT) {
                fontKey = key;
                break;
            }
        }

It appears to be trying to find the base font for the Node. Some controls,
however, define multiple keys of Type.FONT. Axis, for example does this:

public def impl_CSS_KEYS:Key[] = [
    Node.impl_CSS_KEYS,
...
    Key.FONT("-fx-label", Stylesheet.INHERIT),
...
    Key.FONT("-fx-tick-label", Stylesheet.INHERIT),
...
];

As a result, the code in StyleHelper.transitionToState may not always be
doing what was intended.

I have no great thoughts on this one.