LibWeb: Fix calculation of hypothetical cross size in column flex layout

Simplify automatic cross sizing of items in flex-direction:column by
using the fit-content width directly.

There's obviously a lot more nuance to this, but for now this makes
flex items with both width:auto and height:auto actually get some height
in column flex layouts.

Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp

@@ -836,11 +836,16 @@ void FlexFormattingContext::determine_hypothetical_cross_size_of_item(FlexItem&
     } else {
         // Item has indefinite main size, layout with "fit-content"
 
-        float fit_content_main_size;
-        if (is_row_layout())
-            fit_content_main_size = calculate_fit_content_width(item.box, m_available_space->main);
-        else
-            fit_content_main_size = calculate_fit_content_height(item.box, m_available_space->main);
+        // If we're in a column layout and looking for the width, just use the fit-content width.
+        if (!is_row_layout()) {
+            item.hypothetical_cross_size = calculate_fit_content_width(item.box, m_available_space->cross);
+            return;
+        }
+
+        // We're in a row layout, looking for the height. Figure out the fit-content width,
+        // then layout with that and see what height comes out of it.
+
+        float fit_content_main_size = calculate_fit_content_width(item.box, m_available_space->main);
 
         FormattingState throwaway_state(&m_state);
         auto& box_state = throwaway_state.get_mutable(item.box);
@@ -850,18 +855,10 @@ void FlexFormattingContext::determine_hypothetical_cross_size_of_item(FlexItem&
         // NOTE: Flex items should always create an independent formatting context!
         VERIFY(independent_formatting_context);
 
-        if (is_row_layout()) {
-            box_state.content_width = fit_content_main_size;
-        } else {
-            box_state.content_height = fit_content_main_size;
-        }
+        box_state.content_width = fit_content_main_size;
         independent_formatting_context->run(item.box, LayoutMode::Default);
 
-        if (is_row_layout()) {
-            item.hypothetical_cross_size = BlockFormattingContext::compute_theoretical_height(throwaway_state, item.box);
-        } else {
-            item.hypothetical_cross_size = box_state.content_width;
-        }
+        item.hypothetical_cross_size = BlockFormattingContext::compute_theoretical_height(throwaway_state, item.box);
     }
 }