Store abspos boxes in a RefCell too

We want to mutate them when lazily computing their content sizes, but they
are behind an Arc for the hoisting infra, so it also needs its own layer
of inner mutability.

1 files changed, 12 insertions, 6 deletions

diff --git a/components/layout_2020/flow/construct.rs b/components/layout_2020/flow/construct.rs
index 4219bc7bf47..bd2d0bce23d 100644
--- a/components/layout_2020/flow/construct.rs
+++ b/components/layout_2020/flow/construct.rs
@@ -571,9 +571,14 @@ where
                 kind,
             });
         } else {
-            let box_ = ArcRefCell::new(InlineLevelBox::OutOfFlowAbsolutelyPositionedBox(Arc::new(
-                AbsolutelyPositionedBox::construct(self.context, info, display_inside, contents),
-            )));
+            let box_ = ArcRefCell::new(InlineLevelBox::OutOfFlowAbsolutelyPositionedBox(
+                ArcRefCell::new(AbsolutelyPositionedBox::construct(
+                    self.context,
+                    info,
+                    display_inside,
+                    contents,
+                )),
+            ));
             self.current_inline_level_boxes().push(box_.clone());
             box_slot.set(LayoutBox::InlineLevel(box_))
         }
@@ -722,10 +727,11 @@ where
                 display_inside,
                 contents,
             } => {
-                let block_level_box =
-                    ArcRefCell::new(BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(Arc::new(
+                let block_level_box = ArcRefCell::new(
+                    BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(ArcRefCell::new(
                         AbsolutelyPositionedBox::construct(context, info, display_inside, contents),
-                    )));
+                    )),
+                );
                 (block_level_box, ContainsFloats::No)
             },
             BlockLevelCreator::OutOfFlowFloatBox {