Fix #4675: Comment tooltip doesn't show properly on phone.

Possible fix for #4675. This is still wonky; tapping the menu icon now
opens the menu, but doesn't close it. You have to tap outside the menu
to hide it.

app/components/popup_menu_component/popup_menu_component.js

@@ -10,6 +10,7 @@ class PopupMenuComponent {
       target: "a.popup-menu-button",
       placement: "bottom-start",
       trigger: "click",
+      touch: "hold",
       animation: null,
       content: PopupMenuComponent.content,
     });