New alert component doesn't appear to support classic alerts.

Problem/Motivation

Version 5.5.17 introduced components, including the alert component. The alert component's template, components/alert/alert.twig has an outer wrapper with the class "alert-wrapper" which was used in previous and current versions of this theme for the "Alert bottom" message widget. The "Alert bottom" and "Alert classic" message widgets use the same alert component so the "Alert classic" message widgets display like the "Alert bottom" widget, at the bottom of the window.

Steps to reproduce

Configure the messages widget to "Alert classic". Trigger the display of a message, e.g. flush the Drupal cache. Observe the alert appears at the bottom of the browser window, like the "Alert bottom" message widget.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes