layout: Simplify `Contents` a little (#32487)

Instead of duplicating some of `NonReplacedContents` in `Contents`,
divide it into either replaced and non-replaced content, since this is
how the layout system processes `Contents` always. In addition, stop
using `TryInto` to match replaced or non-replaced contents, as it is
quite confusing to handle an `Err` as a success case.

2 files changed, 8 insertions, 8 deletions

diff --git a/components/layout_2020/flow/construct.rs b/components/layout_2020/flow/construct.rs
index 5a53bbd12d9..986ae3e46d7 100644
--- a/components/layout_2020/flow/construct.rs
+++ b/components/layout_2020/flow/construct.rs
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use std::borrow::Cow;
-use std::convert::{TryFrom, TryInto};
+use std::convert::TryFrom;
 
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use servo_arc::Arc;
@@ -401,7 +401,7 @@ where
             DisplayInside::Flow {
                 is_list_item: false,
             },
-            Contents::OfPseudoElement(contents),
+            NonReplacedContents::OfPseudoElement(contents).into(),
             BoxSlot::dummy(),
         );
     }
@@ -494,8 +494,8 @@ where
         }
 
         let propagated_text_decoration_line = self.text_decoration_line;
-        let kind = match contents.try_into() {
-            Ok(contents) => match display_inside {
+        let kind = match contents {
+            Contents::NonReplaced(contents) => match display_inside {
                 DisplayInside::Flow { is_list_item }
                     if !info.style.establishes_block_formatting_context() =>
                 {
@@ -513,7 +513,7 @@ where
                     propagated_text_decoration_line,
                 },
             },
-            Err(contents) => {
+            Contents::Replaced(contents) => {
                 let contents = Contents::Replaced(contents);
                 BlockLevelCreator::Independent {
                     display_inside,
diff --git a/components/layout_2020/flow/root.rs b/components/layout_2020/flow/root.rs
index cea4063592c..8a1865621cb 100644
--- a/components/layout_2020/flow/root.rs
+++ b/components/layout_2020/flow/root.rs
@@ -18,7 +18,7 @@ use webrender_traits::display_list::ScrollSensitivity;
 use crate::cell::ArcRefCell;
 use crate::context::LayoutContext;
 use crate::dom::{LayoutBox, NodeExt};
-use crate::dom_traversal::{iter_child_nodes, Contents, NodeAndStyleInfo};
+use crate::dom_traversal::{iter_child_nodes, Contents, NodeAndStyleInfo, NonReplacedContents};
 use crate::flexbox::FlexLevelBox;
 use crate::flow::float::FloatBox;
 use crate::flow::inline::InlineItem;
@@ -206,7 +206,7 @@ impl BoxTree {
         loop {
             if let Some((primary_style, display_inside, update_point)) = update_point(dirty_node) {
                 let contents = ReplacedContent::for_element(dirty_node, context)
-                    .map_or(Contents::OfElement, Contents::Replaced);
+                    .map_or_else(|| NonReplacedContents::OfElement.into(), Contents::Replaced);
                 let info = NodeAndStyleInfo::new(dirty_node, Arc::clone(&primary_style));
                 let out_of_flow_absolutely_positioned_box = ArcRefCell::new(
                     AbsolutelyPositionedBox::construct(context, &info, display_inside, contents),
@@ -264,7 +264,7 @@ fn construct_for_root_element<'dom>(
     };
 
     let contents = ReplacedContent::for_element(root_element, context)
-        .map_or(Contents::OfElement, Contents::Replaced);
+        .map_or_else(|| NonReplacedContents::OfElement.into(), Contents::Replaced);
     let root_box = if box_style.position.is_absolutely_positioned() {
         BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(ArcRefCell::new(
             AbsolutelyPositionedBox::construct(context, &info, display_inside, contents),