From bdf2323b3f8dc3711b9ebb6951006381cc6578db Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Tue, 5 Sep 2023 15:17:10 -0400
Subject: [PATCH] LibWeb: Perform layout of a slot's assigned nodes

---
 Userland/Libraries/LibWeb/Layout/TreeBuilder.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Userland/Libraries/LibWeb/Layout/TreeBuilder.cpp b/Userland/Libraries/LibWeb/Layout/TreeBuilder.cpp
index cd76a95bab..56ce152697 100644
--- a/Userland/Libraries/LibWeb/Layout/TreeBuilder.cpp
+++ b/Userland/Libraries/LibWeb/Layout/TreeBuilder.cpp
@@ -21,6 +21,7 @@
 #include <LibWeb/HTML/HTMLButtonElement.h>
 #include <LibWeb/HTML/HTMLInputElement.h>
 #include <LibWeb/HTML/HTMLProgressElement.h>
+#include <LibWeb/HTML/HTMLSlotElement.h>
 #include <LibWeb/Layout/ListItemBox.h>
 #include <LibWeb/Layout/ListItemMarkerBox.h>
 #include <LibWeb/Layout/Node.h>
@@ -342,6 +343,19 @@ ErrorOr<void> TreeBuilder::create_layout_tree(DOM::Node& dom_node, TreeBuilder::
         layout_node->append_child(*list_item_marker);
     }
 
+    if (is<HTML::HTMLSlotElement>(dom_node)) {
+        auto slottables = static_cast<HTML::HTMLSlotElement&>(dom_node).assigned_nodes_internal();
+        push_parent(verify_cast<NodeWithStyle>(*layout_node));
+
+        for (auto const& slottable : slottables) {
+            TRY(slottable.visit([&](auto& node) -> ErrorOr<void> {
+                return create_layout_tree(node, context);
+            }));
+        }
+
+        pop_parent();
+    }
+
     if (is<HTML::HTMLProgressElement>(dom_node)) {
         auto& progress = static_cast<HTML::HTMLProgressElement&>(dom_node);
         if (!progress.using_system_appearance()) {