12 files declare their use of Unicode

bootstrap.inc in drupal/core/includes/bootstrap.inc
Functions that need to be loaded on every Drupal request.
Color.php in drupal/core/lib/Drupal/Core/Utility/Color.php
Definition of Drupal\Core\Utility\Color.
common.inc in drupal/core/includes/common.inc
Common functions that many Drupal modules will need to reference.
DbLogController.php in drupal/core/modules/dblog/lib/Drupal/dblog/Controller/DbLogController.php
Contains \Drupal\dblog\Controller\DbLogController.
EditLoadingTest.php in drupal/core/modules/edit/lib/Drupal/edit/Tests/EditLoadingTest.php
Contains \Drupal\edit\Tests\EditLoadingTest.
GlossaryTest.php in drupal/core/modules/views/lib/Drupal/views/Tests/GlossaryTest.php
Definition of Drupal\views\Tests\GlossaryTest.
HandlerBase.php in drupal/core/modules/views/lib/Drupal/views/Plugin/views/HandlerBase.php
Definition of Drupal\views\Plugin\views\HandlerBase.
MachineNameController.php in drupal/core/modules/system/lib/Drupal/system/MachineNameController.php
Contains \Drupal\system\MachineNameController.
search.module in drupal/core/modules/search/search.module
Enables site-wide keyword searching.
theme.maintenance.inc in drupal/core/includes/theme.maintenance.inc
Theming for maintenance pages.
unicode.inc in drupal/core/includes/unicode.inc
Provides Unicode-related conversions and operations.
UnicodeTest.php in drupal/core/tests/Drupal/Tests/Component/Utility/UnicodeTest.php
Contains \Drupal\Tests\Component\Utility\UnicodeTest.