LibWeb: Implement CSS 'contain' property

Author: https://github.com/Psychpsyo
Commit: 67ed676831
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3296
Reviewed-by: https://github.com/AtkinsSJ ✅

Libraries/LibWeb/Layout/Box.cpp

@@ -28,6 +28,37 @@ Box::~Box()
 {
 }
 
+Optional<CSSPixels> Box::natural_width() const
+{
+    // https://drafts.csswg.org/css-contain-2/#containment-size
+    // Replaced elements must be treated as having a natural width and height of 0 and no natural aspect
+    // ratio.
+    if (dom_node() && dom_node()->is_element() && as<DOM::Element>(dom_node())->has_size_containment())
+        return 0;
+
+    return m_natural_width;
+}
+Optional<CSSPixels> Box::natural_height() const
+{
+    // https://drafts.csswg.org/css-contain-2/#containment-size
+    // Replaced elements must be treated as having a natural width and height of 0 and no natural aspect
+    // ratio.
+    if (dom_node() && dom_node()->is_element() && as<DOM::Element>(dom_node())->has_size_containment())
+        return 0;
+
+    return m_natural_height;
+}
+Optional<CSSPixelFraction> Box::natural_aspect_ratio() const
+{
+    // https://drafts.csswg.org/css-contain-2/#containment-size
+    // Replaced elements must be treated as having a natural width and height of 0 and no natural aspect
+    // ratio.
+    if (dom_node() && dom_node()->is_element() && as<DOM::Element>(dom_node())->has_size_containment())
+        return {};
+
+    return m_natural_aspect_ratio;
+}
+
 void Box::visit_edges(Cell::Visitor& visitor)
 {
     Base::visit_edges(visitor);