Issue #3238915: Refactor (if feasible) uses of the jQuery ready function to use VanillaJS

core/tests/Drupal/Tests/Core/DrupalKernel/DrupalKernelLegacyTest.php

-<?php
-
-namespace Drupal\Tests\Core\DrupalKernel;
-
-use Drupal\Core\DrupalKernel;
-use Drupal\Tests\UnitTestCase;
-use Symfony\Component\HttpFoundation\Request;
-use Symfony\Component\HttpKernel\Event\KernelEvent;
-
-/**
- * @coversDefaultClass \Drupal\Core\DrupalKernel
- * @group legacy
- */
-class DrupalKernelLegacyTest extends UnitTestCase {
-
-  /**
-   * Tests deprecation message in overridden KernelEvent.
-   *
-   * @covers ::isMasterRequest
-   */
-  public function testKernelEventDeprecation() {
-    $kernel = $this->createMock(DrupalKernel::class);
-    $request = $this->createMock(Request::class);
-    $event = new KernelEvent($kernel, $request, $kernel::MAIN_REQUEST);
-
-    $this->expectDeprecation('Since symfony/http-kernel 5.3: "Symfony\Component\HttpKernel\Event\KernelEvent::isMasterRequest()" is deprecated, use "isMainRequest()" instead.');
-    $this->assertTrue($event->isMasterRequest());
-  }
-
-}