LibWeb: Calculate available space for children of the grid

Previously were not passing along any information to the children
of the grid, as were simply passing the same AvailableSpace that was
received for the grid itself. Now, each child is given an available
space in accordance with the layout of the grid.

Userland/Libraries/LibWeb/Layout/GridFormattingContext.cpp

@@ -661,8 +661,6 @@ void GridFormattingContext::run(Box const& box, LayoutMode, AvailableSpace const
         auto& child_box_state = m_state.get_mutable(positioned_box.box);
         if (child_box_state.content_height() > positioned_box.computed_height)
             positioned_box.computed_height = child_box_state.content_height();
-        if (auto independent_formatting_context = layout_inside(positioned_box.box, LayoutMode::Normal, available_space))
-            independent_formatting_context->parent_context_did_dimension_child_root_box();
         if (child_box_state.content_height() > positioned_box.computed_height)
             positioned_box.computed_height = child_box_state.content_height();
         if (auto min_content_height = calculate_min_content_height(positioned_box.box, available_space.width); min_content_height > positioned_box.computed_height)
@@ -1470,6 +1468,10 @@ void GridFormattingContext::run(Box const& box, LayoutMode, AvailableSpace const
         child_box_state.set_content_width(x_end - x_start);
         child_box_state.set_content_height(y_end - y_start);
         child_box_state.offset = { x_start, y_start };
+
+        auto available_space_for_children = AvailableSpace(AvailableSize::make_definite(child_box_state.content_width()), AvailableSize::make_definite(child_box_state.content_height()));
+        if (auto independent_formatting_context = layout_inside(child_box, LayoutMode::Normal, available_space_for_children))
+            independent_formatting_context->parent_context_did_dimension_child_root_box();
     };
 
     for (auto& positioned_box : positioned_boxes) {