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

core/includes/bootstrap.inc

core/includes/common.inc

core/includes/file.inc

core/includes/form.inc

core/includes/language.inc

core/includes/path.inc

core/includes/stream_wrappers.inc

core/includes/theme.inc

core/includes/utility.inc

core/lib/Drupal/Component/Uuid/Com.php

core/lib/Drupal/Component/Uuid/Pecl.php

core/lib/Drupal/Component/Uuid/Php.php

core/lib/Drupal/Component/Uuid/Uuid.php

core/lib/Drupal/Component/Uuid/UuidInterface.php

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

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

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

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

core/lib/Drupal/Core/Database/Query/Condition.php

core/lib/Drupal/Core/Utility/CacheArray.php