From 7d37585e3cb15212f70a41127b01cdac0f1eba79 Mon Sep 17 00:00:00 2001
From: catch <catch@35733.no-reply.drupal.org>
Date: Sun, 27 Sep 2015 09:55:26 +0100
Subject: [PATCH] Issue #2511306 by ElusiveMind, JeroenT, leolando.tan: Error:
 Call to a member function getElementsByTagName() in filter.module

---
 core/lib/Drupal/Component/Utility/Html.php     | 18 ++++++++++--------
 .../Tests/Component/Utility/HtmlTest.php       | 15 ++++++++++++++-
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/core/lib/Drupal/Component/Utility/Html.php b/core/lib/Drupal/Component/Utility/Html.php
index 76e05414413..69adbebe796 100644
--- a/core/lib/Drupal/Component/Utility/Html.php
+++ b/core/lib/Drupal/Component/Utility/Html.php
@@ -292,14 +292,16 @@ EOD;
     $body_node = $document->getElementsByTagName('body')->item(0);
     $html = '';
 
-    foreach ($body_node->getElementsByTagName('script') as $node) {
-      static::escapeCdataElement($node);
-    }
-    foreach ($body_node->getElementsByTagName('style') as $node) {
-      static::escapeCdataElement($node, '/*', '*/');
-    }
-    foreach ($body_node->childNodes as $node) {
-      $html .= $document->saveXML($node);
+    if ($body_node !== NULL) {
+      foreach ($body_node->getElementsByTagName('script') as $node) {
+        static::escapeCdataElement($node);
+      }
+      foreach ($body_node->getElementsByTagName('style') as $node) {
+        static::escapeCdataElement($node, '/*', '*/');
+      }
+      foreach ($body_node->childNodes as $node) {
+        $html .= $document->saveXML($node);
+      }
     }
     return $html;
   }
diff --git a/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php b/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php
index bca26232988..42984c425aa 100644
--- a/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php
@@ -312,4 +312,17 @@ class HtmlTest extends UnitTestCase {
     $this->assertSame('&lt;em&gt;répété&lt;/em&gt;', $escaped);
   }
 
-}
+  /**
+   * Tests Html::serialize().
+   *
+   * Resolves an issue by where an empty DOMDocument object sent to serialization would
+   * cause errors in getElementsByTagName() in the serialization function.
+   *
+   * @covers ::serialize
+   */
+  public function testSerialize() {
+    $document = new \DOMDocument();
+    $result = Html::serialize($document);
+    $this->assertSame('', $result);
+  }
+}
\ No newline at end of file