Issue #2088121 by nod_, RobLoach, joelpittet, Gábor Hojtsy: Remove Overlay.

core/CHANGELOG.txt

core/MAINTAINERS.txt

core/assets/vendor/jquery-bbq/jquery.ba-bbq.js

core/misc/dialog.position.js

core/misc/displace.js

core/misc/tabbingmanager.js

core/modules/block/block.module

core/modules/contextual/contextual.module

core/modules/contextual/js/contextual.toolbar.js

core/modules/overlay/css/overlay-child.css

core/modules/overlay/css/overlay-parent.css

core/modules/overlay/images/background.png

core/modules/overlay/images/close.png

...y/lib/Drupal/overlay/Access/DismissMessageAccessCheck.php

...erlay/lib/Drupal/overlay/Controller/OverlayController.php

.../lib/Drupal/overlay/EventSubscriber/OverlaySubscriber.php

...les/overlay/lib/Drupal/overlay/Tests/OverlayCloseTest.php

...es/overlay/lib/Drupal/overlay/Tests/OverlayRenderTest.php

...s/overlay/lib/Drupal/overlay/Tests/OverlaySettingTest.php

core/modules/overlay/overlay-child.js