LibJS+LibWeb: Wrap raw JS::Cell*/& fields in GCPtr/NonnullGCPtr

Author: https://github.com/mattco98
Commit: 7c0c1c8f49
Pull-request: https://github.com/SerenityOS/serenity/pull/17743
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibWeb/Layout/LineBoxFragment.cpp

@@ -37,7 +37,7 @@ StringView LineBoxFragment::text() const
 CSSPixelRect const LineBoxFragment::absolute_rect() const
 {
     CSSPixelRect rect { {}, size() };
-    rect.set_location(m_layout_node.containing_block()->paint_box()->absolute_position());
+    rect.set_location(m_layout_node->containing_block()->paint_box()->absolute_position());
     rect.translate_by(offset());
     return rect;
 }