Issue #2352155 by Wim Leers: Remove HtmlFragment/HtmlPage.

core/authorize.php

core/core.services.yml

core/includes/batch.inc

core/includes/common.inc

core/includes/errors.inc

core/includes/install.core.inc

core/includes/menu.inc

core/includes/theme.inc

core/lib/Drupal/Core/Controller/DialogController.php

core/lib/Drupal/Core/Controller/HtmlControllerBase.php

core/lib/Drupal/Core/Controller/HtmlPageController.php

core/lib/Drupal/Core/CoreServiceProvider.php

core/lib/Drupal/Core/Display/Annotation/DisplayVariant.php

...upal/Core/EventSubscriber/ContentControllerSubscriber.php

.../Core/EventSubscriber/ContentFormControllerSubscriber.php

...rupal/Core/EventSubscriber/DefaultExceptionSubscriber.php

core/lib/Drupal/Core/EventSubscriber/HtmlViewSubscriber.php

...Drupal/Core/EventSubscriber/MainContentViewSubscriber.php

...Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php

core/lib/Drupal/Core/EventSubscriber/ViewSubscriber.php