From 6d830e63353d11a828625152e3f0299faab8bf66 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Thu, 20 Oct 2022 18:20:34 +0200
Subject: [PATCH] LibWeb: Tie layout tree to a specific browsing context

Now that both the layout tree and browsing context are GC-allocated,
we can formalize their relationship a bit better by having layout
nodes keep a NonnullGCPtr to the browsing context.

This makes the previously-indirect link direct, removing an unpleasant
"how do we know the browsing context is alive" question when accessing
it from the layout tree.
---
 Userland/Libraries/LibWeb/Layout/Node.cpp | 8 ++++----
 Userland/Libraries/LibWeb/Layout/Node.h   | 2 ++
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/Userland/Libraries/LibWeb/Layout/Node.cpp b/Userland/Libraries/LibWeb/Layout/Node.cpp
index 778e3cf4a9..f4ddba2d2f 100644
--- a/Userland/Libraries/LibWeb/Layout/Node.cpp
+++ b/Userland/Libraries/LibWeb/Layout/Node.cpp
@@ -20,6 +20,7 @@ namespace Web::Layout {
 
 Node::Node(DOM::Document& document, DOM::Node* node)
     : m_dom_node(node ? *node : document)
+    , m_browsing_context(*document.browsing_context())
     , m_anonymous(node == nullptr)
 {
     m_serial_id = document.next_layout_node_serial_id({});
@@ -34,6 +35,7 @@ void Node::visit_edges(Cell::Visitor& visitor)
 {
     Base::visit_edges(visitor);
     visitor.visit(m_dom_node);
+    visitor.visit(m_browsing_context);
     TreeNode::visit_edges(visitor);
 }
 
@@ -105,14 +107,12 @@ bool Node::establishes_stacking_context() const
 
 HTML::BrowsingContext const& Node::browsing_context() const
 {
-    VERIFY(document().browsing_context());
-    return *document().browsing_context();
+    return *m_browsing_context;
 }
 
 HTML::BrowsingContext& Node::browsing_context()
 {
-    VERIFY(document().browsing_context());
-    return *document().browsing_context();
+    return *m_browsing_context;
 }
 
 InitialContainingBlock const& Node::root() const
diff --git a/Userland/Libraries/LibWeb/Layout/Node.h b/Userland/Libraries/LibWeb/Layout/Node.h
index b3a044d3f8..240fe1b773 100644
--- a/Userland/Libraries/LibWeb/Layout/Node.h
+++ b/Userland/Libraries/LibWeb/Layout/Node.h
@@ -152,6 +152,8 @@ private:
     JS::NonnullGCPtr<DOM::Node> m_dom_node;
     RefPtr<Painting::Paintable> m_paintable;
 
+    JS::NonnullGCPtr<HTML::BrowsingContext> m_browsing_context;
+
     size_t m_serial_id { 0 };
 
     bool m_anonymous { false };