diff -u b/core/tests/Drupal/FunctionalJavascriptTests/JSWebAssert.php b/core/tests/Drupal/FunctionalJavascriptTests/JSWebAssert.php
--- b/core/tests/Drupal/FunctionalJavascriptTests/JSWebAssert.php
+++ b/core/tests/Drupal/FunctionalJavascriptTests/JSWebAssert.php
@@ -371,27 +371,48 @@
    *
+   * @param int $code
+   *
    * @throws \Exception
    *   Throws an exception on use.
-   *
-   * @deprecated in Drupal 8.4.x, will be removed before Drupal 8.5.x. Use an
-   *             assertion on the DOM to validate what is expected. For example
-   *             assert that an element is available on the page.
    */
   public function statusCodeEquals($code) {
-    throw new \Exception('The use of statusCodeEquals() is not available in a functional JavaScript test.');
+    throw new UnsupportedDriverActionException('The use of statusCodeEquals() is not available in a functional JavaScript test.');
   }
 
   /**
    * The use of statusCodeNotEquals() is not available in a functional JavaScript test.
    *
+   * @param int $code
+   *
    * @throws \Exception
    *   Throws an exception on use.
-   *
-   * @deprecated in Drupal 8.4.x, will be removed before Drupal 8.5.x. Use an
-   *             assertion on the DOM to validate what is expected. For example
-   *             assert that an element is not available on the page.
    */
   public function statusCodeNotEquals($code) {
-    throw new \Exception('The use of statusCodeNotEquals() is not available in a functional JavaScript test.');
+    throw new UnsupportedDriverActionException('The use of statusCodeNotEquals() is not available in a functional JavaScript test.');
   }
 
+  /**
+   * The use of responseHeaderEquals() is not available in a functional JavaScript test.
+   *
+   * @param string $name
+   * @param string $value
+   *
+   * @throws \Exception
+   *   Throws an exception on use.
+   */
+  public function responseHeaderEquals($name, $value) {
+    throw new UnsupportedDriverActionException('The use of responseHeaderEquals() is not available in a functional JavaScript test.');
+  }
+
+  /**
+   * The use of responseHeaderNotEquals() is not available in a functional JavaScript test.
+   *
+   * @param string $name
+   * @param string $value
+   *
+   * @throws \Exception
+   *   Throws an exception on use.
+   */
+  public function responseHeaderNotEquals($name, $value) {
+    throw new UnsupportedDriverActionException('The use of responseHeaderEquals() is not available in a functional JavaScript test.');
+  }
 }
reverted:
--- b/core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php
+++ a/core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php
@@ -2,8 +2,6 @@
 
 namespace Drupal\FunctionalJavascriptTests;
 
-use Drupal\Core\Session\AccountInterface;
-use Drupal\Core\Session\AnonymousUserSession;
 use Drupal\Tests\BrowserTestBase;
 use Zumba\GastonJS\Exception\DeadClient;
 use Zumba\Mink\Driver\PhantomJSDriver;
@@ -66,44 +64,6 @@
   }
 
   /**
-   * {@inheritdoc}
-   */
-  protected function drupalLogin(AccountInterface $account) {
-    if ($this->loggedInUser) {
-      $this->drupalLogout();
-    }
-
-    $this->drupalGet('user/login');
-    $page = $this->getSession()->getPage();
-    $page->fillField('name', $account->getAccountName());
-    $page->fillField('pass', $account->passRaw);
-    $page->findButton('Log in')->click();
-
-    $account->sessionId = $this->getSession()->getCookie($this->getSessionName());
-    $this->assertTrue($this->drupalUserIsLoggedIn($account));
-
-    $this->loggedInUser = $account;
-    $this->container->get('current_user')->setAccount($account);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function drupalLogout() {
-    // Make a request to the logout page, and redirect to the user page, the
-    // idea being if you were properly logged out you should be seeing a login
-    // screen.
-    $assert_session = $this->assertSession();
-    $this->drupalGet('user/logout', array('query' => array('destination' => 'user')));
-    $assert_session->fieldExists('name');
-    $assert_session->fieldExists('pass');
-    $this->assertFalse($this->loggedInUser);
-
-    $this->loggedInUser = FALSE;
-    $this->container->get('current_user')->setAccount(new AnonymousUserSession());
-  }
-
-  /**
    * Asserts that the element with the given CSS selector is visible.
    *
    * @param string $css_selector
only in patch2:
unchanged:
--- a/core/tests/Drupal/Tests/BrowserTestBase.php
+++ b/core/tests/Drupal/Tests/BrowserTestBase.php
@@ -714,7 +714,6 @@ protected function drupalLogin(AccountInterface $account) {
     }
 
     $this->drupalGet('user/login');
-    $this->assertSession()->statusCodeEquals(200);
     $this->submitForm(array(
       'name' => $account->getUsername(),
       'pass' => $account->passRaw,
@@ -739,7 +738,6 @@ protected function drupalLogout() {
     // screen.
     $assert_session = $this->assertSession();
     $this->drupalGet('user/logout', array('query' => array('destination' => 'user')));
-    $assert_session->statusCodeEquals(200);
     $assert_session->fieldExists('name');
     $assert_session->fieldExists('pass');