phpcs fixes

core/tests/Drupal/Tests/BrowserHtmlDebugTrait.php

@@ -106,7 +106,7 @@ protected function getHtmlOutputHeaders() {
    *
    * @see \Drupal\Tests\Listeners\VerbosePrinter::printResult()
    *
-   * @return void
+   * @phpstan-ignore missingType.return
    */
   protected function htmlOutput($message = NULL) {
     if (!$this->htmlOutputEnabled) {
@@ -126,7 +126,7 @@ protected function htmlOutput($message = NULL) {
   /**
    * Creates the directory to store browser output.
    *
-   * @return void
+   * @phpstan-ignore missingType.return
    */
   protected function initBrowserOutputFile() {
     $browserOutputFile = getenv('BROWSERTEST_OUTPUT_FILE');

core/tests/Drupal/Tests/HttpKernelUiHelperTrait.php

@@ -10,7 +10,6 @@
 use Behat\Mink\Selector\SelectorsHandler;
 use Behat\Mink\Session;
 use Drupal\Core\Url;
-use Drupal\Tests\WebAssert;
 use Symfony\Component\HttpKernel\HttpKernelBrowser;
 
 /**