LibWeb: Improve FIXME message about getComputedStyle() properties

Let's log which property we're trying to look up, since that's the most
interesting part!

Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp

@@ -196,14 +196,14 @@ static RefPtr<StyleValue const> style_value_for_shadow(Vector<ShadowData> const&
 
 RefPtr<StyleValue const> ResolvedCSSStyleDeclaration::style_value_for_property(Layout::NodeWithStyle const& layout_node, PropertyID property_id) const
 {
-    auto used_value_for_property = [&layout_node](Function<CSSPixels(Painting::PaintableBox const&)>&& used_value_getter) -> Optional<CSSPixels> {
+    auto used_value_for_property = [&layout_node, property_id](Function<CSSPixels(Painting::PaintableBox const&)>&& used_value_getter) -> Optional<CSSPixels> {
         auto const& display = layout_node.computed_values().display();
         if (!display.is_none() && !display.is_contents() && layout_node.paintable()) {
             if (layout_node.paintable()->is_paintable_box()) {
                 auto const& paintable_box = static_cast<Painting::PaintableBox const&>(*layout_node.paintable());
                 return used_value_getter(paintable_box);
             }
-            dbgln("FIXME: Support getting used value for ({})", layout_node.debug_description());
+            dbgln("FIXME: Support getting used value for property `{}` on {}", string_from_property_id(property_id), layout_node.debug_description());
         }
         return {};
     };