21 files declare their use of DrupalKernel

authorize.php in core/authorize.php
Administrative script for running authorized file operations.
BootableCommandTrait.php in core/lib/Drupal/Core/Command/BootableCommandTrait.php
common.inc in core/includes/common.inc
Common functions that many Drupal modules will need to reference.
db-tools.php in core/scripts/db-tools.php
A command line application to import a database generation script.
dump-database-d8-mysql.php in core/scripts/dump-database-d8-mysql.php
A command line application to dump a database to a generation script.
ExtensionDiscovery.php in core/lib/Drupal/Core/Extension/ExtensionDiscovery.php
FunctionalTestSetupTrait.php in core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php
generate-proxy-class.php in core/scripts/generate-proxy-class.php
A script to generate proxy classes for lazy services.
index.php in ./index.php
The PHP page that serves all page requests on a Drupal installation.
index.php in core/assets/scaffold/files/index.php
The PHP page that serves all page requests on a Drupal installation.
install.core.inc in core/includes/install.core.inc
API functions for installing Drupal.
InstallCommand.php in core/lib/Drupal/Core/Command/InstallCommand.php
InstallerKernel.php in core/lib/Drupal/Core/Installer/InstallerKernel.php
PublicStream.php in core/lib/Drupal/Core/StreamWrapper/PublicStream.php
rebuild.php in core/rebuild.php
Rebuilds all Drupal caches even when Drupal itself does not work.
ServerCommand.php in core/lib/Drupal/Core/Command/ServerCommand.php
system.install in core/modules/system/system.install
Install, update and uninstall functions for the system module.
TestKernel.php in core/lib/Drupal/Core/Test/TestKernel.php
TestRunnerKernel.php in core/lib/Drupal/Core/Test/TestRunnerKernel.php
UpdateKernel.php in core/lib/Drupal/Core/Update/UpdateKernel.php
utility.inc in core/includes/utility.inc
Miscellaneous functions.