layout: Add incremental box tree construction for inline atomics (#37866)

This changes extend the incremental box tree construction for inline
atomic

Testing: This should not change observable behavior and is thus covered
by existing WPT tests.

Signed-off-by: sharpshooter_pt <ibluegalaxy_taoj@163.com>

components/layout/flow/construct.rs

@@ -290,7 +290,7 @@ impl<'dom, 'style> BlockContainerBuilder<'dom, 'style> {
 
         if inline_table {
             self.ensure_inline_formatting_context_builder()
-                .push_atomic(ifc);
+                .push_atomic(|| ArcRefCell::new(ifc), None);
         } else {
             let table_block = ArcRefCell::new(BlockLevelBox::Independent(ifc));
 
@@ -472,15 +472,20 @@ impl<'dom> BlockContainerBuilder<'dom, '_> {
                 // If this inline element is an atomic, handle it and return.
                 let context = self.context;
                 let propagated_data = self.propagated_data;
-                let atomic = self.ensure_inline_formatting_context_builder().push_atomic(
-                    IndependentFormattingContext::construct(
+
+                let construction_callback = || {
+                    ArcRefCell::new(IndependentFormattingContext::construct(
                         context,
                         info,
                         display_inside,
                         contents,
                         propagated_data,
-                    ),
-                );
+                    ))
+                };
+                let old_layout_box = box_slot.take_layout_box_if_undamaged(info.damage);
+                let atomic = self
+                    .ensure_inline_formatting_context_builder()
+                    .push_atomic(construction_callback, old_layout_box);
                 box_slot.set(LayoutBox::InlineLevel(vec![atomic]));
                 return;
             },

components/layout/flow/inline/construct.rs

@@ -18,6 +18,7 @@ use super::{
 };
 use crate::cell::ArcRefCell;
 use crate::context::LayoutContext;
+use crate::dom::LayoutBox;
 use crate::dom_traversal::NodeAndStyleInfo;
 use crate::flow::float::FloatBox;
 use crate::formatting_contexts::IndependentFormattingContext;
@@ -153,10 +154,30 @@ impl InlineFormattingContextBuilder {
 
     pub(crate) fn push_atomic(
         &mut self,
-        independent_formatting_context: IndependentFormattingContext,
+        independent_formatting_context_creator: impl FnOnce()
+            -> ArcRefCell<IndependentFormattingContext>,
+        old_layout_box: Option<LayoutBox>,
     ) -> ArcRefCell<InlineItem> {
+        // If there is an existing undamaged layout box that's compatible, use that.
+        let independent_formatting_context = old_layout_box
+            .and_then(|layout_box| {
+                let LayoutBox::InlineLevel(inline_level_boxes) = layout_box else {
+                    return None;
+                };
+
+                // If there's an existing box, it should be a compatible atomic inline and should
+                // not have been subject to inline-block splitting.
+                assert_eq!(inline_level_boxes.len(), 1);
+                let first_box = inline_level_boxes.into_iter().next()?;
+                match &*first_box.borrow() {
+                    InlineItem::Atomic(atomic, ..) => Some(atomic.clone()),
+                    _ => None,
+                }
+            })
+            .unwrap_or_else(independent_formatting_context_creator);
+
         let inline_level_box = ArcRefCell::new(InlineItem::Atomic(
-            ArcRefCell::new(independent_formatting_context),
+            independent_formatting_context,
             self.current_text_offset,
             Level::ltr(), /* This will be assigned later if necessary. */
         ));