core/lib/Drupal/Core/Render/HtmlResponseAttachmentsProcessor.php | 1 -
 core/modules/book/src/Tests/BookTest.php                         | 1 -
 2 files changed, 2 deletions(-)

diff --git a/core/lib/Drupal/Core/Render/HtmlResponseAttachmentsProcessor.php b/core/lib/Drupal/Core/Render/HtmlResponseAttachmentsProcessor.php
index afcdcd0..cc20063 100644
--- a/core/lib/Drupal/Core/Render/HtmlResponseAttachmentsProcessor.php
+++ b/core/lib/Drupal/Core/Render/HtmlResponseAttachmentsProcessor.php
@@ -162,7 +162,6 @@ public function processAttachments(AttachmentsInterface $response) {
    * @see \Drupal\Core\Render\Renderer::renderPlaceholder()
    */
   protected function renderPlaceholders(HtmlResponse $response) {
-    // Render the placeholders in the HTML Response object.
     $build = [
       '#markup' => SafeString::create($response->getContent()),
       '#attached' => $response->getAttachments(),
diff --git a/core/modules/book/src/Tests/BookTest.php b/core/modules/book/src/Tests/BookTest.php
index d2394cd..b530265 100644
--- a/core/modules/book/src/Tests/BookTest.php
+++ b/core/modules/book/src/Tests/BookTest.php
@@ -116,7 +116,6 @@ function createBook() {
    * @see \Drupal\book\Cache\BookNavigationCacheContext
    */
   public function testBookNavigationCacheContext() {
-    $this->dumpHeaders = TRUE;
     // Create a page node.
     $this->drupalCreateContentType(['type' => 'page']);
     $page = $this->drupalCreateNode();