Ensure that we provide the `source` parameter when dispatching the button click events in `SecondaryToolbar` (PR 7313 follow-up)

web/secondary_toolbar.js

@@ -127,7 +127,7 @@ var SecondaryToolbar = (function SecondaryToolbarClosure() {
 
         element.addEventListener('click', function (eventName, close) {
           if (eventName !== null) {
-            this.eventBus.dispatch(eventName);
+            this.eventBus.dispatch(eventName, { source: this, });
           }
           if (close) {
             this.close();