diff --git a/components/style/animation.rs b/components/style/animation.rs
index 68316f8ed5f..f7f639532f8 100644
--- a/components/style/animation.rs
+++ b/components/style/animation.rs
@@ -12,10 +12,12 @@ use crate::bezier::Bezier;
 use crate::context::SharedStyleContext;
 use crate::dom::{OpaqueNode, TElement};
 use crate::font_metrics::FontMetricsProvider;
-use crate::properties::animated_properties::{AnimatedProperty, TransitionPropertyIteration};
+use crate::properties::animated_properties::AnimatedProperty;
 use crate::properties::longhands::animation_direction::computed_value::single_value::T as AnimationDirection;
 use crate::properties::longhands::animation_play_state::computed_value::single_value::T as AnimationPlayState;
-use crate::properties::{self, CascadeMode, ComputedValues, LonghandId, LonghandIdSet};
+#[cfg(feature = "servo")]
+use crate::properties::LonghandIdSet;
+use crate::properties::{self, CascadeMode, ComputedValues, LonghandId};
 use crate::stylesheets::keyframes_rule::{KeyframesAnimation, KeyframesStep, KeyframesStepValue};
 use crate::stylesheets::Origin;
 use crate::timer::Timer;
@@ -432,6 +434,8 @@ pub fn start_transitions_if_applicable(
     expired_transitions: &[PropertyAnimation],
     running_animations: &[Animation],
 ) -> LonghandIdSet {
+    use crate::properties::animated_properties::TransitionPropertyIteration;
+
     // If the style of this element is display:none, then we don't start any transitions
     // and we cancel any currently running transitions by returning an empty LonghandIdSet.
     if new_style.get_box().clone_display().is_none() {
diff --git a/components/style/rule_tree/core.rs b/components/style/rule_tree/core.rs
index d1c8bda5379..ae1ba7bed94 100644
--- a/components/style/rule_tree/core.rs
+++ b/components/style/rule_tree/core.rs
@@ -202,6 +202,9 @@ impl RuleTree {
 /// where it likely did not result from a rigorous performance analysis.)
 const RULE_TREE_GC_INTERVAL: usize = 300;
 
+/// Used for some size assertions.
+pub const RULE_NODE_SIZE: usize = std::mem::size_of::<RuleNode>();
+
 /// A node in the rule tree.
 struct RuleNode {
     /// The root node. Only the root has no root pointer, for obvious reasons.
diff --git a/components/style/rule_tree/mod.rs b/components/style/rule_tree/mod.rs
index ab5273db781..e50382255ca 100644
--- a/components/style/rule_tree/mod.rs
+++ b/components/style/rule_tree/mod.rs
@@ -19,7 +19,7 @@ mod map;
 mod source;
 mod unsafe_box;
 
-pub use self::core::{RuleTree, StrongRuleNode};
+pub use self::core::{RuleTree, StrongRuleNode, RULE_NODE_SIZE};
 pub use self::level::{CascadeLevel, ShadowCascadeOrder};
 pub use self::source::StyleSource;