aboutToHide is emitted before an action is triggered and activeAction() is the action currently hovered.
This means we can't properly tell that the prompt got canceled, when hovering an action and then hitting Escape to close the menu.
This patch sets a property in response to triggered and then does a delayed check for that in aboutToHide.

5.18 please
Used https://alligator.io/js/web-share-api/ for testing

• Clicked "Share me!" button, got purpose prompt, clicked Email, shared correctly
• Clicked "Share me!" button, got purpose prompt, clicked outside, canceled correctly

With this patch

• Clicked "Share me!" button, hovered an action, then hit Escape to cancel it. Now cancels properly.

Previously it would effectively break the plugin as it would never reset its pending reply state.