LibWeb: Only calculate intrinsic size in the desired flex axis

Previously, FlexFormattingContext would calculate intrinsic sizes in
both axes simultaneously, despite only one being needed.

This patch reduces the amount of unnecessary work by only calculating
the requested intrinsic size.

Author: awesomekling

Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp

@@ -1396,15 +1396,13 @@ void FlexFormattingContext::copy_dimensions_from_flex_items_to_boxes()
 // https://drafts.csswg.org/css-flexbox-1/#intrinsic-sizes
 void FlexFormattingContext::determine_intrinsic_size_of_flex_container()
 {
-    float main_size = calculate_intrinsic_main_size_of_flex_container();
-    float cross_size = calculate_intrinsic_cross_size_of_flex_container();
-
-    if (is_row_layout()) {
-        m_flex_container_state.set_content_width(main_size);
-        m_flex_container_state.set_content_height(cross_size);
-    } else {
-        m_flex_container_state.set_content_height(main_size);
-        m_flex_container_state.set_content_width(cross_size);
+    if (m_available_space_for_flex_container->main.is_intrinsic_sizing_constraint()) {
+        float main_size = calculate_intrinsic_main_size_of_flex_container();
+        set_main_size(flex_container(), main_size);
+    }
+    if (m_available_space_for_items->cross.is_intrinsic_sizing_constraint()) {
+        float cross_size = calculate_intrinsic_cross_size_of_flex_container();
+        set_cross_size(flex_container(), cross_size);
     }
 }