fix(UI): Don't allow click on the buttons when the UI is not visible (#8396)

ui/ad_statistics_button.js

@@ -127,6 +127,9 @@ shaka.ui.AdStatisticsButton = class extends shaka.ui.Element {
         });
 
     this.eventManager.listen(this.button_, 'click', () => {
+      if (!this.controls.isOpaque()) {
+        return;
+      }
       this.onClick_();
       this.updateLocalizedStrings_();
     });