LibWeb: Position abspos children of flex container after parent layout

If we wait until after the parent context has laid out the flex
container, abspos children are able to use the final results of the
parent sizing the flex container.

This makes `height:auto` work on abspos children of a flex container.

2 files changed, 5 insertions, 0 deletions

diff --git a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
index adbe120da0..a1b9652ccc 100644
--- a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
+++ b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
@@ -136,7 +136,10 @@ void FlexFormattingContext::run(Box const& run_box, LayoutMode layout_mode)
     //        part of the spec, and simply covering up the fact that our inside layout currently
     //        mutates the height of BFC roots.
     copy_dimensions_from_flex_items_to_boxes();
+}
 
+void FlexFormattingContext::parent_context_did_dimension_child_root_box()
+{
     flex_container().for_each_child_of_type<Box>([&](Layout::Box& box) {
         if (box.is_absolutely_positioned())
             layout_absolutely_positioned_element(box);
diff --git a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h
index ceb9f44346..b02929f34d 100644
--- a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h
+++ b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h
@@ -164,6 +164,8 @@ private:
     [[nodiscard]] float calculate_fit_content_main_size(FlexItem const&) const;
     [[nodiscard]] float calculate_fit_content_cross_size(FlexItem const&) const;
 
+    virtual void parent_context_did_dimension_child_root_box() override;
+
     CSS::FlexBasisData used_flex_basis_for_item(FlexItem const&) const;
 
     LayoutState::UsedValues& m_flex_container_state;