Issue #2090353 by dawehner: Don't require to put the use statement into plugin classes.

...al/Component/Plugin/Discovery/AnnotatedClassDiscovery.php

.../Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php

core/modules/contact/lib/Drupal/contact/Entity/Message.php

...odules/menu_link/lib/Drupal/menu_link/Entity/MenuLink.php

core/modules/node/lib/Drupal/node/Entity/Node.php

core/modules/user/lib/Drupal/user/Entity/Role.php

core/modules/user/lib/Drupal/user/Entity/User.php

core/modules/views/lib/Drupal/views/Entity/View.php

...les/views/lib/Drupal/views/Plugin/views/row/EntityRow.php

...iews/lib/Drupal/views/Plugin/views/style/DefaultStyle.php