diff --git a/core/lib/Drupal/Core/Extension/Discovery/RecursiveExtensionFilterIterator.php b/core/lib/Drupal/Core/Extension/Discovery/RecursiveExtensionFilterIterator.php
index fc9b445..b158175 100644
--- a/core/lib/Drupal/Core/Extension/Discovery/RecursiveExtensionFilterIterator.php
+++ b/core/lib/Drupal/Core/Extension/Discovery/RecursiveExtensionFilterIterator.php
@@ -71,6 +71,7 @@ class RecursiveExtensionFilterIterator extends \RecursiveFilterIterator {
     'js',
     'misc',
     'templates',
+    // Deeply nested Node.js subdirectories.
     'node_modules',
     'bower_components',
     // Legacy subdirectories.