support better alerts on non-safari browser/screen reader combos, phe…

…tsims/scenery-phet#490

js/AriaHerald.js

@@ -30,6 +30,7 @@ import Emitter from '../../axon/js/Emitter.js';
 import stepTimer from '../../axon/js/stepTimer.js';
 import Enumeration from '../../phet-core/js/Enumeration.js';
 import merge from '../../phet-core/js/merge.js';
+import platform from '../../phet-core/js/platform.js';
 import PDOMUtils from '../../scenery/js/accessibility/pdom/PDOMUtils.js';
 import utteranceQueueNamespace from './utteranceQueueNamespace.js';
 
@@ -163,9 +164,15 @@ class AriaHerald {
       // https://github.com/phetsims/scenery-phet/issues/491
       stepTimer.setTimeout( () => {
 
-        // Using `hidden` rather than clearing textContent works better on mobile VO,
-        // see https://github.com/phetsims/scenery-phet/issues/490
-        liveElement.hidden = true;
+        if ( platform.safari ) {
+
+          // Using `hidden` rather than clearing textContent works better on mobile VO,
+          // see https://github.com/phetsims/scenery-phet/issues/490
+          liveElement.hidden = true;
+        }
+        else {
+          liveElement.textContent = '';
+        }
       }, 200 );
     }, 0 );
   }