Issue #2256317 by sun: Remove static caching from WebTestBase::checkPermissions().

core/modules/block/lib/Drupal/block/Tests/BlockTestBase.php

...ent/lib/Drupal/comment/Tests/CommentTranslationUITest.php

...ilter/lib/Drupal/filter/Tests/FilterDefaultFormatTest.php

...filter/lib/Drupal/filter/Tests/FilterFormatAccessTest.php

...ter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php

core/modules/rest/lib/Drupal/rest/Tests/RESTTestBase.php

.../modules/simpletest/lib/Drupal/simpletest/WebTestBase.php

...y/lib/Drupal/taxonomy/Tests/VocabularyPermissionsTest.php

core/modules/text/lib/Drupal/text/Tests/TextFieldTest.php

.../modules/user/lib/Drupal/user/Tests/UserSignatureTest.php

core/modules/views/lib/Drupal/views/Tests/ViewTestBase.php