disable AriaHerald when a11y not enabled, https://github.com/phetsims/joist/issues/454 https://github.com/phetsims/scenery/issues/710
disable AriaHerald when a11y not enabled, https://github.com/phetsims/joist/issues/454 https://github.com/phetsims/scenery/issues/710

phetsims/scenery-phet,phetsims/scenery-phet,phetsims/scenery-phet