From ba6a9318c37e8d4e60d86e84524ed817064270f6 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Sat, 29 Oct 2022 13:16:32 +0200
Subject: [PATCH] LibWeb: Don't update style/layout in template contents owner
 documents

These helper documents don't actually get rendered, so computing style
and doing layout for them is a complete waste of work.
---
 Userland/Libraries/LibWeb/DOM/Document.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Userland/Libraries/LibWeb/DOM/Document.cpp b/Userland/Libraries/LibWeb/DOM/Document.cpp
index 91e6a333b5..865bf0338f 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Document.cpp
@@ -809,6 +809,10 @@ void Document::update_layout()
     if (!m_needs_layout && m_layout_root)
         return;
 
+    // NOTE: If this is a document hosting <template> contents, layout is unnecessary.
+    if (m_created_for_appropriate_template_contents)
+        return;
+
     if (!browsing_context())
         return;
 
@@ -886,6 +890,11 @@ void Document::update_style()
         return;
     if (!needs_full_style_update() && !needs_style_update() && !child_needs_style_update())
         return;
+
+    // NOTE: If this is a document hosting <template> contents, style update is unnecessary.
+    if (m_created_for_appropriate_template_contents)
+        return;
+
     evaluate_media_rules();
     if (update_style_recursively(*this))
         invalidate_layout();