Merge remote-tracking branch 'upstream/8.x' into kernel

core/MAINTAINERS.txt

core/includes/bootstrap.inc

core/includes/form.inc

core/includes/module.inc

core/includes/session.inc

core/lib/Drupal/Core/Cache/DatabaseBackend.php

core/lib/Drupal/Core/Database/Driver/pgsql/Install/Tasks.php

core/lib/Drupal/Core/Database/Driver/pgsql/Transaction.php

core/misc/drupal.js

core/misc/form.js

core/misc/machine-name.js

core/misc/tableheader.js

core/modules/aggregator/aggregator.module

core/modules/block/block.module

core/modules/book/book.module

core/modules/color/color.module

core/modules/comment/comment.module

core/modules/contact/contact.module

core/modules/contextual/contextual.module

core/modules/dashboard/dashboard.js