Make resolveStyle() public.

There are times when it's needed and you're not in a subclass of Element<?>.
Make it possible to use custom EffectRenderers.

Do so thusly:

button.addStyles(Style.TEXT_EFFECT.is(new EffectFactory() {
  public EffectRenderer createEffectRenderer (Element<?> elem) {
    // use Styles.resolveStyle(elem, Style.FOO) to get parameters
    return /* my custom effect renderer */;
  }
}));