Add animation and transition support for pseudo-elements

This change extends the DocumentAnimationSet to hold animations for
pseudo-elements. Since pseudo-elements in Servo are not in the DOM like
in Gecko, they need to be handled a bit carefully in stylo.  When a
pseudo-element has an animation, recascade the style. Finally, this
change passes the pseudo-element string properly to animation events.

Fixes: #10316

1 files changed, 7 insertions, 3 deletions

diff --git a/components/layout_2020/flow/root.rs b/components/layout_2020/flow/root.rs
index 55c325a3cd0..0d346a34eeb 100644
--- a/components/layout_2020/flow/root.rs
+++ b/components/layout_2020/flow/root.rs
@@ -38,6 +38,7 @@ use servo_arc::Arc;
 use style::animation::AnimationSetKey;
 use style::dom::OpaqueNode;
 use style::properties::ComputedValues;
+use style::selector_parser::PseudoElement;
 use style::values::computed::Length;
 use style_traits::CSSPixel;
 
@@ -449,9 +450,12 @@ impl FragmentTree {
 
     pub fn remove_nodes_in_fragment_tree_from_set(&self, set: &mut FxHashSet<AnimationSetKey>) {
         self.find(|fragment, _| {
-            if let Some(tag) = fragment.tag().as_ref() {
-                set.remove(&AnimationSetKey(tag.node()));
-            }
+            let (node, pseudo) = match fragment.tag()? {
+                Tag::Node(node) => (node, None),
+                Tag::BeforePseudo(node) => (node, Some(PseudoElement::Before)),
+                Tag::AfterPseudo(node) => (node, Some(PseudoElement::After)),
+            };
+            set.remove(&AnimationSetKey::new(node, pseudo));
             None::<()>
         });
     }