diff --git a/Cargo.lock b/Cargo.lock
index 4128623a867..8a380de7442 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4680,6 +4680,7 @@ dependencies = [
 name = "script_traits"
 version = "0.0.1"
 dependencies = [
+ "bitflags",
  "bluetooth_traits",
  "canvas_traits",
  "cookie",
diff --git a/components/compositing/compositor.rs b/components/compositing/compositor.rs
index 5a495ed1aa8..c3c545af4bb 100644
--- a/components/compositing/compositor.rs
+++ b/components/compositing/compositor.rs
@@ -1042,20 +1042,22 @@ impl<Window: WindowMethods + ?Sized> IOCompositor<Window> {
         let animation_callbacks_running = self
             .pipeline_details(pipeline_id)
             .animation_callbacks_running;
-        if animation_callbacks_running {
-            let msg = ConstellationMsg::TickAnimation(pipeline_id, AnimationTickType::Script);
-            if let Err(e) = self.constellation_chan.send(msg) {
-                warn!("Sending tick to constellation failed ({:?}).", e);
-            }
+        let animations_running = self.pipeline_details(pipeline_id).animations_running;
+        if !animation_callbacks_running && !animations_running {
+            return;
         }
 
-        // We may need to tick animations in layout. (See #12749.)
-        let animations_running = self.pipeline_details(pipeline_id).animations_running;
+        let mut tick_type = AnimationTickType::empty();
         if animations_running {
-            let msg = ConstellationMsg::TickAnimation(pipeline_id, AnimationTickType::Layout);
-            if let Err(e) = self.constellation_chan.send(msg) {
-                warn!("Sending tick to constellation failed ({:?}).", e);
-            }
+            tick_type.insert(AnimationTickType::CSS_ANIMATIONS_AND_TRANSITIONS);
+        }
+        if animation_callbacks_running {
+            tick_type.insert(AnimationTickType::REQUEST_ANIMATION_FRAME);
+        }
+
+        let msg = ConstellationMsg::TickAnimation(pipeline_id, tick_type);
+        if let Err(e) = self.constellation_chan.send(msg) {
+            warn!("Sending tick to constellation failed ({:?}).", e);
         }
     }
 
diff --git a/components/constellation/constellation.rs b/components/constellation/constellation.rs
index a2647bd2a45..00dcd2a4eb8 100644
--- a/components/constellation/constellation.rs
+++ b/components/constellation/constellation.rs
@@ -3458,27 +3458,13 @@ where
     }
 
     fn handle_tick_animation(&mut self, pipeline_id: PipelineId, tick_type: AnimationTickType) {
-        let result = match tick_type {
-            AnimationTickType::Script => {
-                let msg = ConstellationControlMsg::TickAllAnimations(pipeline_id);
-                match self.pipelines.get(&pipeline_id) {
-                    Some(pipeline) => pipeline.event_loop.send(msg),
-                    None => {
-                        return warn!("Pipeline {:?} got script tick after closure.", pipeline_id);
-                    },
-                }
-            },
-            AnimationTickType::Layout => match self.pipelines.get(&pipeline_id) {
-                Some(pipeline) => {
-                    let msg = LayoutControlMsg::TickAnimations(pipeline.load_data.url.origin());
-                    pipeline.layout_chan.send(msg)
-                },
-                None => {
-                    return warn!("Pipeline {:?} got layout tick after closure.", pipeline_id);
-                },
-            },
+        let pipeline = match self.pipelines.get(&pipeline_id) {
+            Some(pipeline) => pipeline,
+            None => return warn!("Pipeline {:?} got script tick after closure.", pipeline_id),
         };
-        if let Err(e) = result {
+
+        let message = ConstellationControlMsg::TickAllAnimations(pipeline_id, tick_type);
+        if let Err(e) = pipeline.event_loop.send(message) {
             self.handle_send_error(pipeline_id, e);
         }
     }
diff --git a/components/layout/animation.rs b/components/layout/animation.rs
index 64c1dfd2e0a..09e3c75ec2c 100644
--- a/components/layout/animation.rs
+++ b/components/layout/animation.rs
@@ -4,7 +4,6 @@
 
 //! CSS transitions and animations.
 
-use crate::context::LayoutContext;
 use crate::display_list::items::OpaqueNode;
 use crate::flow::{Flow, GetBaseFlow};
 use crate::opaque_node::OpaqueNodeMethods;
@@ -16,54 +15,27 @@ use script_traits::{
     AnimationState, ConstellationControlMsg, LayoutMsg as ConstellationMsg,
     TransitionOrAnimationEventType,
 };
-use servo_arc::Arc;
-use style::animation::{update_style_for_animation, Animation, ElementAnimationState};
-use style::dom::TElement;
-use style::font_metrics::ServoMetricsProvider;
-use style::selector_parser::RestyleDamage;
-use style::timer::Timer;
+use style::animation::{Animation, ElementAnimationState};
 
-/// Collect newly animating nodes, which is used by the script process during
-/// forced, synchronous reflows to root DOM nodes for the duration of their
-/// animations or transitions.
-pub fn collect_newly_animating_nodes(
-    animation_states: &FxHashMap<OpaqueNode, ElementAnimationState>,
-    mut out: Option<&mut Vec<UntrustedNodeAddress>>,
-) {
-    // This extends the output vector with an iterator that contains a copy of the node
-    // address for every new animation. This is a bit goofy, but the script thread
-    // currently stores a rooted node for every property that is transitioning.
-    if let Some(ref mut out) = out {
-        out.extend(animation_states.iter().flat_map(|(node, state)| {
-            std::iter::repeat(node.to_untrusted_node_address()).take(state.new_animations.len())
-        }));
-    }
-}
-
-/// Processes any new animations that were discovered after style recalculation. Also
-/// finish any animations that have completed, inserting them into `finished_animations`.
-pub fn update_animation_states(
+/// Processes any new animations that were discovered after style recalculation and
+/// remove animations for any disconnected nodes. Send messages that trigger events
+/// for any events that changed state.
+pub fn do_post_style_animations_update(
     constellation_chan: &IpcSender<ConstellationMsg>,
     script_chan: &IpcSender<ConstellationControlMsg>,
     animation_states: &mut FxHashMap<OpaqueNode, ElementAnimationState>,
-    invalid_nodes: FxHashSet<OpaqueNode>,
     pipeline_id: PipelineId,
-    timer: &Timer,
+    now: f64,
+    out: &mut Vec<UntrustedNodeAddress>,
+    root_flow: &mut dyn Flow,
 ) {
     let had_running_animations = animation_states
         .values()
         .any(|state| !state.running_animations.is_empty());
 
-    // Cancel all animations on any invalid nodes. These entries will later
-    // be removed from the list of states, because their states will become
-    // empty.
-    for node in &invalid_nodes {
-        if let Some(mut state) = animation_states.remove(node) {
-            state.cancel_all_animations();
-        }
-    }
+    cancel_animations_for_disconnected_nodes(animation_states, root_flow);
+    collect_newly_animating_nodes(animation_states, out);
 
-    let now = timer.seconds();
     let mut have_running_animations = false;
     for (node, animation_state) in animation_states.iter_mut() {
         update_animation_state(script_chan, animation_state, pipeline_id, now, *node);
@@ -89,7 +61,50 @@ pub fn update_animation_states(
         .unwrap();
 }
 
-pub fn update_animation_state(
+/// Collect newly animating nodes, which is used by the script process during
+/// forced, synchronous reflows to root DOM nodes for the duration of their
+/// animations or transitions.
+pub fn collect_newly_animating_nodes(
+    animation_states: &FxHashMap<OpaqueNode, ElementAnimationState>,
+    out: &mut Vec<UntrustedNodeAddress>,
+) {
+    // This extends the output vector with an iterator that contains a copy of the node
+    // address for every new animation. This is a bit goofy, but the script thread
+    // currently stores a rooted node for every property that is transitioning.
+    out.extend(animation_states.iter().flat_map(|(node, state)| {
+        std::iter::repeat(node.to_untrusted_node_address()).take(state.new_animations.len())
+    }));
+}
+
+/// Cancel animations for any nodes which have been removed from the DOM or are display:none.
+/// We detect this by looking for nodes that are used in the flow tree.
+/// TODO(mrobinson): We should look into a way of doing this during flow tree construction.
+/// This also doesn't yet handles nodes that have been reparented.
+pub fn cancel_animations_for_disconnected_nodes(
+    animation_states: &mut FxHashMap<OpaqueNode, ElementAnimationState>,
+    root_flow: &mut dyn Flow,
+) {
+    // Assume all nodes have been removed until proven otherwise.
+    let mut invalid_nodes: FxHashSet<OpaqueNode> = animation_states.keys().cloned().collect();
+    fn traverse_flow(flow: &mut dyn Flow, invalid_nodes: &mut FxHashSet<OpaqueNode>) {
+        flow.mutate_fragments(&mut |fragment| {
+            invalid_nodes.remove(&fragment.node);
+        });
+        for kid in flow.mut_base().children.iter_mut() {
+            traverse_flow(kid, invalid_nodes)
+        }
+    }
+    traverse_flow(root_flow, &mut invalid_nodes);
+
+    // Cancel animations for any nodes that are no longer in the flow tree.
+    for node in &invalid_nodes {
+        if let Some(state) = animation_states.get_mut(node) {
+            state.cancel_all_animations();
+        }
+    }
+}
+
+fn update_animation_state(
     script_channel: &IpcSender<ConstellationControlMsg>,
     animation_state: &mut ElementAnimationState,
     pipeline_id: PipelineId,
@@ -122,36 +137,28 @@ pub fn update_animation_state(
 
 /// Walk through the list of running animations and remove all of the ones that
 /// have ended.
-pub fn handle_running_animations(
+fn handle_running_animations(
     animation_state: &mut ElementAnimationState,
     now: f64,
     mut send_event: impl FnMut(&Animation, TransitionOrAnimationEventType, f64),
 ) {
+    if animation_state.running_animations.is_empty() {
+        return;
+    }
+
     let mut running_animations =
         std::mem::replace(&mut animation_state.running_animations, Vec::new());
-    for mut running_animation in running_animations.drain(..) {
-        let still_running = match running_animation {
-            Animation::Transition(_, started_at, ref property_animation) => {
-                now < started_at + (property_animation.duration)
-            },
-            Animation::Keyframes(_, _, _, ref mut state) => {
-                // This animation is still running, or we need to keep
-                // iterating.
-                now < state.started_at + state.duration || state.tick()
-            },
-        };
-
+    for running_animation in running_animations.drain(..) {
         // If the animation is still running, add it back to the list of running animations.
-        if still_running {
+        if !running_animation.has_ended(now) {
             animation_state.running_animations.push(running_animation);
         } else {
-            debug!("Finishing transition: {:?}", running_animation);
             let (event_type, elapsed_time) = match running_animation {
                 Animation::Transition(_, _, ref property_animation) => (
                     TransitionOrAnimationEventType::TransitionEnd,
                     property_animation.duration,
                 ),
-                Animation::Keyframes(_, _, _, ref mut state) => (
+                Animation::Keyframes(_, _, _, ref state) => (
                     TransitionOrAnimationEventType::AnimationEnd,
                     state.active_duration(),
                 ),
@@ -166,7 +173,7 @@ pub fn handle_running_animations(
 /// Send events for cancelled animations. Currently this only handles cancelled
 /// transitions, but eventually this should handle cancelled CSS animations as
 /// well.
-pub fn handle_cancelled_animations(
+fn handle_cancelled_animations(
     animation_state: &mut ElementAnimationState,
     now: f64,
     mut send_event: impl FnMut(&Animation, TransitionOrAnimationEventType, f64),
@@ -188,7 +195,7 @@ pub fn handle_cancelled_animations(
     }
 }
 
-pub fn handle_new_animations(
+fn handle_new_animations(
     animation_state: &mut ElementAnimationState,
     mut send_event: impl FnMut(&Animation, TransitionOrAnimationEventType, f64),
 ) {
@@ -208,55 +215,3 @@ pub fn handle_new_animations(
         animation_state.running_animations.push(animation);
     }
 }
-
-/// Recalculates style for a set of animations. This does *not* run with the DOM
-/// lock held. Returns a set of nodes associated with animations that are no longer
-/// valid.
-pub fn recalc_style_for_animations<E>(
-    context: &LayoutContext,
-    flow: &mut dyn Flow,
-    animation_states: &FxHashMap<OpaqueNode, ElementAnimationState>,
-) -> FxHashSet<OpaqueNode>
-where
-    E: TElement,
-{
-    let mut invalid_nodes = animation_states.keys().cloned().collect();
-    do_recalc_style_for_animations::<E>(context, flow, animation_states, &mut invalid_nodes);
-    invalid_nodes
-}
-
-fn do_recalc_style_for_animations<E>(
-    context: &LayoutContext,
-    flow: &mut dyn Flow,
-    animation_states: &FxHashMap<OpaqueNode, ElementAnimationState>,
-    invalid_nodes: &mut FxHashSet<OpaqueNode>,
-) where
-    E: TElement,
-{
-    let mut damage = RestyleDamage::empty();
-    flow.mutate_fragments(&mut |fragment| {
-        let animations = match animation_states.get(&fragment.node) {
-            Some(state) => &state.running_animations,
-            None => return,
-        };
-
-        invalid_nodes.remove(&fragment.node);
-        for animation in animations.iter() {
-            let old_style = fragment.style.clone();
-            update_style_for_animation::<E>(
-                &context.style_context,
-                animation,
-                Arc::make_mut(&mut fragment.style),
-                &ServoMetricsProvider,
-            );
-            let difference = RestyleDamage::compute_style_difference(&old_style, &fragment.style);
-            damage |= difference.damage;
-        }
-    });
-
-    let base = flow.mut_base();
-    base.restyle_damage.insert(damage);
-    for kid in base.children.iter_mut() {
-        do_recalc_style_for_animations::<E>(context, kid, animation_states, invalid_nodes)
-    }
-}
diff --git a/components/layout/context.rs b/components/layout/context.rs
index fc243b8234f..536d108ea04 100644
--- a/components/layout/context.rs
+++ b/components/layout/context.rs
@@ -11,8 +11,9 @@ use gfx::font_cache_thread::FontCacheThread;
 use gfx::font_context::FontContext;
 use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
 use msg::constellation_msg::PipelineId;
-use net_traits::image_cache::{CanRequestImages, ImageCache, ImageCacheResult};
-use net_traits::image_cache::{ImageOrMetadataAvailable, UsePlaceholder};
+use net_traits::image_cache::{
+    ImageCache, ImageCacheResult, ImageOrMetadataAvailable, UsePlaceholder,
+};
 use parking_lot::RwLock;
 use script_layout_interface::{PendingImage, PendingImageState};
 use script_traits::Painter;
@@ -83,20 +84,16 @@ pub struct LayoutContext<'a> {
     pub registered_painters: &'a dyn RegisteredPainters,
 
     /// A list of in-progress image loads to be shared with the script thread.
-    /// A None value means that this layout was not initiated by the script thread.
-    pub pending_images: Option<Mutex<Vec<PendingImage>>>,
+    pub pending_images: Mutex<Vec<PendingImage>>,
 
     /// A list of nodes that have just initiated a CSS transition or animation.
-    /// A None value means that this layout was not initiated by the script thread.
-    pub newly_animating_nodes: Option<Mutex<Vec<UntrustedNodeAddress>>>,
+    pub newly_animating_nodes: Mutex<Vec<UntrustedNodeAddress>>,
 }
 
 impl<'a> Drop for LayoutContext<'a> {
     fn drop(&mut self) {
         if !thread::panicking() {
-            if let Some(ref pending_images) = self.pending_images {
-                assert!(pending_images.lock().unwrap().is_empty());
-            }
+            assert!(self.pending_images.lock().unwrap().is_empty());
         }
     }
 }
@@ -113,22 +110,12 @@ impl<'a> LayoutContext<'a> {
         url: ServoUrl,
         use_placeholder: UsePlaceholder,
     ) -> Option<ImageOrMetadataAvailable> {
-        //XXXjdm For cases where we do not request an image, we still need to
-        //       ensure the node gets another script-initiated reflow or it
-        //       won't be requested at all.
-        let can_request = if self.pending_images.is_some() {
-            CanRequestImages::Yes
-        } else {
-            CanRequestImages::No
-        };
-
         // Check for available image or start tracking.
         let cache_result = self.image_cache.get_cached_image_status(
             url.clone(),
             self.origin.clone(),
             None,
             use_placeholder,
-            can_request,
         );
 
         match cache_result {
@@ -136,18 +123,13 @@ impl<'a> LayoutContext<'a> {
             // Image has been requested, is still pending. Return no image for this paint loop.
             // When the image loads it will trigger a reflow and/or repaint.
             ImageCacheResult::Pending(id) => {
-                //XXXjdm if self.pending_images is not available, we should make sure that
-                //       this node gets marked dirty again so it gets a script-initiated
-                //       reflow that deals with this properly.
-                if let Some(ref pending_images) = self.pending_images {
-                    let image = PendingImage {
-                        state: PendingImageState::PendingResponse,
-                        node: node.to_untrusted_node_address(),
-                        id,
-                        origin: self.origin.clone(),
-                    };
-                    pending_images.lock().unwrap().push(image);
-                }
+                let image = PendingImage {
+                    state: PendingImageState::PendingResponse,
+                    node: node.to_untrusted_node_address(),
+                    id,
+                    origin: self.origin.clone(),
+                };
+                self.pending_images.lock().unwrap().push(image);
                 None
             },
             // Not yet requested - request image or metadata from the cache
@@ -158,12 +140,7 @@ impl<'a> LayoutContext<'a> {
                     id,
                     origin: self.origin.clone(),
                 };
-                self.pending_images
-                    .as_ref()
-                    .unwrap()
-                    .lock()
-                    .unwrap()
-                    .push(image);
+                self.pending_images.lock().unwrap().push(image);
                 None
             },
             // Image failed to load, so just return nothing
diff --git a/components/layout_2020/context.rs b/components/layout_2020/context.rs
index 117a02e0940..109a1a6935b 100644
--- a/components/layout_2020/context.rs
+++ b/components/layout_2020/context.rs
@@ -8,8 +8,9 @@ use fnv::FnvHashMap;
 use gfx::font_cache_thread::FontCacheThread;
 use gfx::font_context::FontContext;
 use msg::constellation_msg::PipelineId;
-use net_traits::image_cache::{CanRequestImages, ImageCache, ImageCacheResult};
-use net_traits::image_cache::{ImageOrMetadataAvailable, UsePlaceholder};
+use net_traits::image_cache::{
+    ImageCache, ImageCacheResult, ImageOrMetadataAvailable, UsePlaceholder,
+};
 use parking_lot::RwLock;
 use script_layout_interface::{PendingImage, PendingImageState};
 use servo_url::{ImmutableOrigin, ServoUrl};
@@ -33,8 +34,7 @@ pub struct LayoutContext<'a> {
     pub image_cache: Arc<dyn ImageCache>,
 
     /// A list of in-progress image loads to be shared with the script thread.
-    /// A None value means that this layout was not initiated by the script thread.
-    pub pending_images: Option<Mutex<Vec<PendingImage>>>,
+    pub pending_images: Mutex<Vec<PendingImage>>,
 
     pub webrender_image_cache:
         Arc<RwLock<FnvHashMap<(ServoUrl, UsePlaceholder), WebRenderImageInfo>>>,
@@ -43,9 +43,7 @@ pub struct LayoutContext<'a> {
 impl<'a> Drop for LayoutContext<'a> {
     fn drop(&mut self) {
         if !std::thread::panicking() {
-            if let Some(ref pending_images) = self.pending_images {
-                assert!(pending_images.lock().unwrap().is_empty());
-            }
+            assert!(self.pending_images.lock().unwrap().is_empty());
         }
     }
 }
@@ -62,22 +60,12 @@ impl<'a> LayoutContext<'a> {
         url: ServoUrl,
         use_placeholder: UsePlaceholder,
     ) -> Option<ImageOrMetadataAvailable> {
-        //XXXjdm For cases where we do not request an image, we still need to
-        //       ensure the node gets another script-initiated reflow or it
-        //       won't be requested at all.
-        let can_request = if self.pending_images.is_some() {
-            CanRequestImages::Yes
-        } else {
-            CanRequestImages::No
-        };
-
         // Check for available image or start tracking.
         let cache_result = self.image_cache.get_cached_image_status(
             url.clone(),
             self.origin.clone(),
             None,
             use_placeholder,
-            can_request,
         );
 
         match cache_result {
@@ -85,18 +73,13 @@ impl<'a> LayoutContext<'a> {
             // Image has been requested, is still pending. Return no image for this paint loop.
             // When the image loads it will trigger a reflow and/or repaint.
             ImageCacheResult::Pending(id) => {
-                //XXXjdm if self.pending_images is not available, we should make sure that
-                //       this node gets marked dirty again so it gets a script-initiated
-                //       reflow that deals with this properly.
-                if let Some(ref pending_images) = self.pending_images {
-                    let image = PendingImage {
-                        state: PendingImageState::PendingResponse,
-                        node: node.to_untrusted_node_address(),
-                        id,
-                        origin: self.origin.clone(),
-                    };
-                    pending_images.lock().unwrap().push(image);
-                }
+                let image = PendingImage {
+                    state: PendingImageState::PendingResponse,
+                    node: node.to_untrusted_node_address(),
+                    id,
+                    origin: self.origin.clone(),
+                };
+                self.pending_images.lock().unwrap().push(image);
                 None
             },
             // Not yet requested - request image or metadata from the cache
@@ -107,12 +90,7 @@ impl<'a> LayoutContext<'a> {
                     id,
                     origin: self.origin.clone(),
                 };
-                self.pending_images
-                    .as_ref()
-                    .unwrap()
-                    .lock()
-                    .unwrap()
-                    .push(image);
+                self.pending_images.lock().unwrap().push(image);
                 None
             },
             // Image failed to load, so just return nothing
diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index 046a9a6f30e..38982fa826b 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -29,7 +29,7 @@ use crossbeam_channel::{Receiver, Sender};
 use embedder_traits::resources::{self, Resource};
 use euclid::{default::Size2D as UntypedSize2D, Point2D, Rect, Scale, Size2D};
 use fnv::FnvHashMap;
-use fxhash::{FxHashMap, FxHashSet};
+use fxhash::FxHashMap;
 use gfx::font;
 use gfx::font_cache_thread::FontCacheThread;
 use gfx::font_context;
@@ -88,7 +88,6 @@ use servo_arc::Arc as ServoArc;
 use servo_atoms::Atom;
 use servo_config::opts;
 use servo_config::pref;
-use servo_geometry::MaxRect;
 use servo_url::{ImmutableOrigin, ServoUrl};
 use std::borrow::ToOwned;
 use std::cell::{Cell, RefCell};
@@ -622,7 +621,6 @@ impl LayoutThread {
     fn build_layout_context<'a>(
         &'a self,
         guards: StylesheetGuards<'a>,
-        script_initiated_layout: bool,
         snapshot_map: &'a SnapshotMap,
         origin: ImmutableOrigin,
     ) -> LayoutContext<'a> {
@@ -636,23 +634,15 @@ impl LayoutThread {
                 visited_styles_enabled: false,
                 animation_states: self.animation_states.clone(),
                 registered_speculative_painters: &self.registered_painters,
-                timer: self.timer.clone(),
+                current_time_for_animations: self.timer.seconds(),
                 traversal_flags: TraversalFlags::empty(),
                 snapshot_map: snapshot_map,
             },
             image_cache: self.image_cache.clone(),
             font_cache_thread: Mutex::new(self.font_cache_thread.clone()),
             webrender_image_cache: self.webrender_image_cache.clone(),
-            pending_images: if script_initiated_layout {
-                Some(Mutex::new(vec![]))
-            } else {
-                None
-            },
-            newly_animating_nodes: if script_initiated_layout {
-                Some(Mutex::new(vec![]))
-            } else {
-                None
-            },
+            pending_images: Mutex::new(vec![]),
+            newly_animating_nodes: Mutex::new(vec![]),
             registered_painters: &self.registered_painters,
         }
     }
@@ -664,8 +654,6 @@ impl LayoutThread {
             Msg::SetQuirksMode(..) => LayoutHangAnnotation::SetQuirksMode,
             Msg::Reflow(..) => LayoutHangAnnotation::Reflow,
             Msg::GetRPC(..) => LayoutHangAnnotation::GetRPC,
-            Msg::TickAnimations(..) => LayoutHangAnnotation::TickAnimations,
-            Msg::AdvanceClockMs(..) => LayoutHangAnnotation::AdvanceClockMs,
             Msg::CollectReports(..) => LayoutHangAnnotation::CollectReports,
             Msg::PrepareToExit(..) => LayoutHangAnnotation::PrepareToExit,
             Msg::ExitNow => LayoutHangAnnotation::ExitNow,
@@ -712,9 +700,6 @@ impl LayoutThread {
                     Msg::SetScrollStates(new_scroll_states),
                     possibly_locked_rw_data,
                 ),
-            Request::FromPipeline(LayoutControlMsg::TickAnimations(origin)) => {
-                self.handle_request_helper(Msg::TickAnimations(origin), possibly_locked_rw_data)
-            },
             Request::FromPipeline(LayoutControlMsg::GetCurrentEpoch(sender)) => {
                 self.handle_request_helper(Msg::GetCurrentEpoch(sender), possibly_locked_rw_data)
             },
@@ -786,9 +771,6 @@ impl LayoutThread {
                     || self.handle_reflow(&mut data, possibly_locked_rw_data),
                 );
             },
-            Msg::TickAnimations(origin) => {
-                self.tick_all_animations(possibly_locked_rw_data, origin)
-            },
             Msg::SetScrollStates(new_scroll_states) => {
                 self.set_scroll_states(new_scroll_states, possibly_locked_rw_data);
             },
@@ -813,9 +795,6 @@ impl LayoutThread {
                 let _rw_data = possibly_locked_rw_data.lock();
                 sender.send(self.epoch.get()).unwrap();
             },
-            Msg::AdvanceClockMs(how_many, do_tick, origin) => {
-                self.handle_advance_clock_ms(how_many, possibly_locked_rw_data, do_tick, origin);
-            },
             Msg::GetWebFontLoadState(sender) => {
                 let _rw_data = possibly_locked_rw_data.lock();
                 let outstanding_web_fonts = self.outstanding_web_fonts.load(Ordering::SeqCst);
@@ -993,20 +972,6 @@ impl LayoutThread {
         }
     }
 
-    /// Advances the animation clock of the document.
-    fn handle_advance_clock_ms<'a, 'b>(
-        &mut self,
-        how_many_ms: i32,
-        possibly_locked_rw_data: &mut RwData<'a, 'b>,
-        tick_animations: bool,
-        origin: ImmutableOrigin,
-    ) {
-        self.timer.increment(how_many_ms as f64 / 1000.0);
-        if tick_animations {
-            self.tick_all_animations(possibly_locked_rw_data, origin);
-        }
-    }
-
     /// Sets quirks mode for the document, causing the quirks mode stylesheet to be used.
     fn handle_set_quirks_mode<'a, 'b>(&mut self, quirks_mode: QuirksMode) {
         self.stylist.set_quirks_mode(quirks_mode);
@@ -1341,6 +1306,12 @@ impl LayoutThread {
         let device = Device::new(MediaType::screen(), initial_viewport, device_pixel_ratio);
         let sheet_origins_affected_by_device_change = self.stylist.set_device(device, &guards);
 
+        if pref!(layout.animations.test.enabled) {
+            if let Some(delta) = data.advance_clock_delta {
+                self.timer.increment(delta as f64 / 1000.0);
+            }
+        }
+
         self.stylist
             .force_stylesheet_origins_dirty(sheet_origins_affected_by_device_change);
         self.viewport_size =
@@ -1458,7 +1429,7 @@ impl LayoutThread {
         self.stylist.flush(&guards, Some(element), Some(&map));
 
         // Create a layout context for use throughout the following passes.
-        let mut layout_context = self.build_layout_context(guards.clone(), true, &map, origin);
+        let mut layout_context = self.build_layout_context(guards.clone(), &map, origin);
 
         let pool;
         let (thread_pool, num_threads) = if self.parallel_flag {
@@ -1539,7 +1510,6 @@ impl LayoutThread {
                 Some(&document),
                 &mut rw_data,
                 &mut layout_context,
-                FxHashSet::default(),
             );
         }
 
@@ -1559,17 +1529,10 @@ impl LayoutThread {
         context: &mut LayoutContext,
         reflow_result: &mut ReflowComplete,
     ) {
-        let pending_images = match context.pending_images {
-            Some(ref pending) => std::mem::replace(&mut *pending.lock().unwrap(), vec![]),
-            None => vec![],
-        };
-        reflow_result.pending_images = pending_images;
-
-        let newly_animating_nodes = match context.newly_animating_nodes {
-            Some(ref nodes) => std::mem::replace(&mut *nodes.lock().unwrap(), vec![]),
-            None => vec![],
-        };
-        reflow_result.newly_animating_nodes = newly_animating_nodes;
+        reflow_result.pending_images =
+            std::mem::replace(&mut *context.pending_images.lock().unwrap(), vec![]);
+        reflow_result.newly_animating_nodes =
+            std::mem::replace(&mut *context.newly_animating_nodes.lock().unwrap(), vec![]);
 
         let mut root_flow = match self.root_flow.borrow().clone() {
             Some(root_flow) => root_flow,
@@ -1681,70 +1644,6 @@ impl LayoutThread {
         rw_data.scroll_offsets = layout_scroll_states
     }
 
-    fn tick_all_animations<'a, 'b>(
-        &mut self,
-        possibly_locked_rw_data: &mut RwData<'a, 'b>,
-        origin: ImmutableOrigin,
-    ) {
-        let mut rw_data = possibly_locked_rw_data.lock();
-        self.tick_animations(&mut rw_data, origin);
-    }
-
-    fn tick_animations(&mut self, rw_data: &mut LayoutThreadData, origin: ImmutableOrigin) {
-        if self.relayout_event {
-            println!(
-                "**** pipeline={}\tForDisplay\tSpecial\tAnimationTick",
-                self.id
-            );
-        }
-
-        if let Some(mut root_flow) = self.root_flow.borrow().clone() {
-            let reflow_info = Reflow {
-                page_clip_rect: Rect::max_rect(),
-            };
-
-            // Unwrap here should not panic since self.root_flow is only ever set to Some(_)
-            // in handle_reflow() where self.document_shared_lock is as well.
-            let author_shared_lock = self.document_shared_lock.clone().unwrap();
-            let author_guard = author_shared_lock.read();
-            let ua_or_user_guard = UA_STYLESHEETS.shared_lock.read();
-            let guards = StylesheetGuards {
-                author: &author_guard,
-                ua_or_user: &ua_or_user_guard,
-            };
-            let snapshots = SnapshotMap::new();
-            let mut layout_context = self.build_layout_context(guards, false, &snapshots, origin);
-
-            let invalid_nodes = {
-                // Perform an abbreviated style recalc that operates without access to the DOM.
-                let animation_states = self.animation_states.read();
-                profile(
-                    profile_time::ProfilerCategory::LayoutStyleRecalc,
-                    self.profiler_metadata(),
-                    self.time_profiler_chan.clone(),
-                    || {
-                        animation::recalc_style_for_animations::<ServoLayoutElement>(
-                            &layout_context,
-                            FlowRef::deref_mut(&mut root_flow),
-                            &animation_states,
-                        )
-                    },
-                )
-            };
-            self.perform_post_style_recalc_layout_passes(
-                &mut root_flow,
-                &reflow_info,
-                &ReflowGoal::TickAnimations,
-                None,
-                &mut *rw_data,
-                &mut layout_context,
-                invalid_nodes,
-            );
-            assert!(layout_context.pending_images.is_none());
-            assert!(layout_context.newly_animating_nodes.is_none());
-        }
-    }
-
     fn perform_post_style_recalc_layout_passes(
         &self,
         root_flow: &mut FlowRef,
@@ -1753,23 +1652,17 @@ impl LayoutThread {
         document: Option<&ServoLayoutDocument>,
         rw_data: &mut LayoutThreadData,
         context: &mut LayoutContext,
-        invalid_nodes: FxHashSet<OpaqueNode>,
     ) {
         {
-            let mut newly_animating_nodes = context
-                .newly_animating_nodes
-                .as_ref()
-                .map(|nodes| nodes.lock().unwrap());
-            let newly_animating_nodes = newly_animating_nodes.as_mut().map(|nodes| &mut **nodes);
-            let mut animation_states = self.animation_states.write();
-            animation::collect_newly_animating_nodes(&animation_states, newly_animating_nodes);
-            animation::update_animation_states(
+            let mut newly_animating_nodes = context.newly_animating_nodes.lock().unwrap();
+            animation::do_post_style_animations_update(
                 &self.constellation_chan,
                 &self.script_chan,
-                &mut *animation_states,
-                invalid_nodes,
+                &mut *(self.animation_states.write()),
                 self.id,
-                &self.timer,
+                context.style_context.current_time_for_animations,
+                &mut newly_animating_nodes,
+                FlowRef::deref_mut(root_flow),
             );
         }
 
diff --git a/components/layout_thread_2020/lib.rs b/components/layout_thread_2020/lib.rs
index 1a0d99cdb27..1b8366a4881 100644
--- a/components/layout_thread_2020/lib.rs
+++ b/components/layout_thread_2020/lib.rs
@@ -580,7 +580,6 @@ impl LayoutThread {
     fn build_layout_context<'a>(
         &'a self,
         guards: StylesheetGuards<'a>,
-        script_initiated_layout: bool,
         snapshot_map: &'a SnapshotMap,
         origin: ImmutableOrigin,
     ) -> LayoutContext<'a> {
@@ -601,11 +600,7 @@ impl LayoutThread {
             image_cache: self.image_cache.clone(),
             font_cache_thread: Mutex::new(self.font_cache_thread.clone()),
             webrender_image_cache: self.webrender_image_cache.clone(),
-            pending_images: if script_initiated_layout {
-                Some(Mutex::new(Vec::new()))
-            } else {
-                None
-            },
+            pending_images: Mutex::new(vec![]),
             use_rayon: STYLE_THREAD_POOL.pool().is_some(),
         }
     }
@@ -617,8 +612,6 @@ impl LayoutThread {
             Msg::SetQuirksMode(..) => LayoutHangAnnotation::SetQuirksMode,
             Msg::Reflow(..) => LayoutHangAnnotation::Reflow,
             Msg::GetRPC(..) => LayoutHangAnnotation::GetRPC,
-            Msg::TickAnimations(..) => LayoutHangAnnotation::TickAnimations,
-            Msg::AdvanceClockMs(..) => LayoutHangAnnotation::AdvanceClockMs,
             Msg::CollectReports(..) => LayoutHangAnnotation::CollectReports,
             Msg::PrepareToExit(..) => LayoutHangAnnotation::PrepareToExit,
             Msg::ExitNow => LayoutHangAnnotation::ExitNow,
@@ -665,9 +658,6 @@ impl LayoutThread {
                     Msg::SetScrollStates(new_scroll_states),
                     possibly_locked_rw_data,
                 ),
-            Request::FromPipeline(LayoutControlMsg::TickAnimations(origin)) => {
-                self.handle_request_helper(Msg::TickAnimations(origin), possibly_locked_rw_data)
-            },
             Request::FromPipeline(LayoutControlMsg::GetCurrentEpoch(sender)) => {
                 self.handle_request_helper(Msg::GetCurrentEpoch(sender), possibly_locked_rw_data)
             },
@@ -739,7 +729,6 @@ impl LayoutThread {
                     || self.handle_reflow(&mut data, possibly_locked_rw_data),
                 );
             },
-            Msg::TickAnimations(origin) => self.tick_all_animations(origin),
             Msg::SetScrollStates(new_scroll_states) => {
                 self.set_scroll_states(new_scroll_states, possibly_locked_rw_data);
             },
@@ -764,9 +753,6 @@ impl LayoutThread {
                 let _rw_data = possibly_locked_rw_data.lock();
                 sender.send(self.epoch.get()).unwrap();
             },
-            Msg::AdvanceClockMs(how_many, do_tick, origin) => {
-                self.handle_advance_clock_ms(how_many, do_tick, origin);
-            },
             Msg::GetWebFontLoadState(sender) => {
                 let _rw_data = possibly_locked_rw_data.lock();
                 let outstanding_web_fonts = self.outstanding_web_fonts.load(Ordering::SeqCst);
@@ -900,19 +886,6 @@ impl LayoutThread {
         }
     }
 
-    /// Advances the animation clock of the document.
-    fn handle_advance_clock_ms<'a, 'b>(
-        &mut self,
-        how_many_ms: i32,
-        tick_animations: bool,
-        origin: ImmutableOrigin,
-    ) {
-        self.timer.increment(how_many_ms as f64 / 1000.0);
-        if tick_animations {
-            self.tick_all_animations(origin);
-        }
-    }
-
     /// Sets quirks mode for the document, causing the quirks mode stylesheet to be used.
     fn handle_set_quirks_mode<'a, 'b>(&mut self, quirks_mode: QuirksMode) {
         self.stylist.set_quirks_mode(quirks_mode);
@@ -1004,6 +977,12 @@ impl LayoutThread {
         let device = Device::new(MediaType::screen(), initial_viewport, device_pixel_ratio);
         let sheet_origins_affected_by_device_change = self.stylist.set_device(device, &guards);
 
+        if pref!(layout.animations.test.enabled) {
+            if let Some(delta) = data.advance_clock_delta {
+                self.timer.increment(delta as f64 / 1000.0);
+            }
+        }
+
         self.stylist
             .force_stylesheet_origins_dirty(sheet_origins_affected_by_device_change);
         self.viewport_size =
@@ -1103,7 +1082,7 @@ impl LayoutThread {
         self.stylist.flush(&guards, Some(element), Some(&map));
 
         // Create a layout context for use throughout the following passes.
-        let mut layout_context = self.build_layout_context(guards.clone(), true, &map, origin);
+        let mut layout_context = self.build_layout_context(guards.clone(), &map, origin);
 
         let traversal = RecalcStyle::new(layout_context);
         let token = {
@@ -1195,11 +1174,9 @@ impl LayoutThread {
         context: &mut LayoutContext,
         reflow_result: &mut ReflowComplete,
     ) {
-        let pending_images = match &context.pending_images {
-            Some(pending) => std::mem::take(&mut *pending.lock().unwrap()),
-            None => Vec::new(),
-        };
-        reflow_result.pending_images = pending_images;
+        reflow_result.pending_images =
+            std::mem::replace(&mut *context.pending_images.lock().unwrap(), vec![]);
+
         match *reflow_goal {
             ReflowGoal::LayoutQuery(ref querymsg, _) => match querymsg {
                 &QueryMsg::ContentBoxQuery(node) => {
@@ -1304,41 +1281,6 @@ impl LayoutThread {
         rw_data.scroll_offsets = layout_scroll_states
     }
 
-    fn tick_all_animations<'a, 'b>(&mut self, origin: ImmutableOrigin) {
-        self.tick_animations(origin);
-    }
-
-    fn tick_animations(&mut self, origin: ImmutableOrigin) {
-        if self.relayout_event {
-            println!(
-                "**** pipeline={}\tForDisplay\tSpecial\tAnimationTick",
-                self.id
-            );
-        }
-
-        if let Some(root) = &*self.fragment_tree_root.borrow() {
-            // Unwrap here should not panic since self.fragment_tree_root is only ever set to Some(_)
-            // in handle_reflow() where self.document_shared_lock is as well.
-            let author_shared_lock = self.document_shared_lock.clone().unwrap();
-            let author_guard = author_shared_lock.read();
-            let ua_or_user_guard = UA_STYLESHEETS.shared_lock.read();
-            let guards = StylesheetGuards {
-                author: &author_guard,
-                ua_or_user: &ua_or_user_guard,
-            };
-            let snapshots = SnapshotMap::new();
-            let mut layout_context = self.build_layout_context(guards, false, &snapshots, origin);
-
-            self.perform_post_style_recalc_layout_passes(
-                root.clone(),
-                &ReflowGoal::TickAnimations,
-                None,
-                &mut layout_context,
-            );
-            assert!(layout_context.pending_images.is_none());
-        }
-    }
-
     fn perform_post_style_recalc_layout_passes(
         &self,
         fragment_tree: Arc<FragmentTreeRoot>,
diff --git a/components/msg/constellation_msg.rs b/components/msg/constellation_msg.rs
index ae0ceb39b18..c70021421d6 100644
--- a/components/msg/constellation_msg.rs
+++ b/components/msg/constellation_msg.rs
@@ -530,8 +530,6 @@ pub enum LayoutHangAnnotation {
     SetQuirksMode,
     Reflow,
     GetRPC,
-    TickAnimations,
-    AdvanceClockMs,
     CollectReports,
     PrepareToExit,
     ExitNow,
diff --git a/components/net/image_cache.rs b/components/net/image_cache.rs
index fea75ee7b95..95379770883 100644
--- a/components/net/image_cache.rs
+++ b/components/net/image_cache.rs
@@ -7,8 +7,7 @@ use immeta::load_from_buf;
 use ipc_channel::ipc::IpcSender;
 use net_traits::image::base::{load_from_memory, Image, ImageMetadata};
 use net_traits::image_cache::{
-    CanRequestImages, CorsStatus, ImageCache, ImageCacheResult, ImageResponder,
-    PendingImageResponse,
+    CorsStatus, ImageCache, ImageCacheResult, ImageResponder, PendingImageResponse,
 };
 use net_traits::image_cache::{ImageOrMetadataAvailable, ImageResponse};
 use net_traits::image_cache::{PendingImageId, UsePlaceholder};
@@ -147,7 +146,6 @@ impl AllPendingLoads {
         url: ServoUrl,
         origin: ImmutableOrigin,
         cors_status: Option<CorsSettings>,
-        can_request: CanRequestImages,
     ) -> CacheResult<'a> {
         match self
             .url_to_load_key
@@ -158,10 +156,6 @@ impl AllPendingLoads {
                 CacheResult::Hit(*load_key, self.loads.get_mut(load_key).unwrap())
             },
             Vacant(url_entry) => {
-                if can_request == CanRequestImages::No {
-                    return CacheResult::Miss(None);
-                }
-
                 let load_key = self.keygen.next();
                 url_entry.insert(load_key);
 
@@ -461,7 +455,6 @@ impl ImageCache for ImageCacheImpl {
         origin: ImmutableOrigin,
         cors_setting: Option<CorsSettings>,
         use_placeholder: UsePlaceholder,
-        can_request: CanRequestImages,
     ) -> ImageCacheResult {
         let mut store = self.store.lock().unwrap();
         if let Some(result) = store.get_completed_image_if_available(
@@ -485,12 +478,9 @@ impl ImageCache for ImageCacheImpl {
         }
 
         let decoded = {
-            let result = store.pending_loads.get_cached(
-                url.clone(),
-                origin.clone(),
-                cors_setting,
-                can_request,
-            );
+            let result = store
+                .pending_loads
+                .get_cached(url.clone(), origin.clone(), cors_setting);
             match result {
                 CacheResult::Hit(key, pl) => match (&pl.result, &pl.metadata) {
                     (&Some(Ok(_)), _) => {
@@ -539,7 +529,6 @@ impl ImageCache for ImageCacheImpl {
         cors_setting: Option<CorsSettings>,
         sender: IpcSender<PendingImageResponse>,
         use_placeholder: UsePlaceholder,
-        can_request: CanRequestImages,
     ) -> ImageCacheResult {
         debug!("Track image for {} ({:?})", url, origin);
         let cache_result = self.get_cached_image_status(
@@ -547,7 +536,6 @@ impl ImageCache for ImageCacheImpl {
             origin.clone(),
             cors_setting,
             use_placeholder,
-            can_request,
         );
 
         match cache_result {
diff --git a/components/net_traits/image_cache.rs b/components/net_traits/image_cache.rs
index 9c5ca0b1455..39d501a271f 100644
--- a/components/net_traits/image_cache.rs
+++ b/components/net_traits/image_cache.rs
@@ -14,15 +14,6 @@ use std::sync::Arc;
 // Aux structs and enums.
 // ======================================================================
 
-/// Whether a consumer is in a position to request images or not. This can occur
-/// when animations are being processed by the layout thread while the script
-/// thread is executing in parallel.
-#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Serialize)]
-pub enum CanRequestImages {
-    No,
-    Yes,
-}
-
 /// Indicating either entire image or just metadata availability
 #[derive(Clone, Debug, Deserialize, MallocSizeOf, Serialize)]
 pub enum ImageOrMetadataAvailable {
@@ -119,7 +110,6 @@ pub trait ImageCache: Sync + Send {
         origin: ImmutableOrigin,
         cors_setting: Option<CorsSettings>,
         use_placeholder: UsePlaceholder,
-        can_request: CanRequestImages,
     ) -> ImageCacheResult;
 
     /// Add a listener for the provided pending image id, eventually called by
@@ -135,7 +125,6 @@ pub trait ImageCache: Sync + Send {
         cors_setting: Option<CorsSettings>,
         sender: IpcSender<PendingImageResponse>,
         use_placeholder: UsePlaceholder,
-        can_request: CanRequestImages,
     ) -> ImageCacheResult;
 
     /// Add a new listener for the given pending image id. If the image is already present,
diff --git a/components/script/dom/htmlimageelement.rs b/components/script/dom/htmlimageelement.rs
index 052b622bb9f..595d0d52d41 100644
--- a/components/script/dom/htmlimageelement.rs
+++ b/components/script/dom/htmlimageelement.rs
@@ -60,8 +60,8 @@ use mime::{self, Mime};
 use msg::constellation_msg::PipelineId;
 use net_traits::image::base::{Image, ImageMetadata};
 use net_traits::image_cache::{
-    CanRequestImages, CorsStatus, ImageCache, ImageCacheResult, ImageOrMetadataAvailable,
-    ImageResponse, PendingImageId, PendingImageResponse, UsePlaceholder,
+    CorsStatus, ImageCache, ImageCacheResult, ImageOrMetadataAvailable, ImageResponse,
+    PendingImageId, PendingImageResponse, UsePlaceholder,
 };
 use net_traits::request::{CorsSettings, Destination, Initiator, RequestBuilder};
 use net_traits::{FetchMetadata, FetchResponseListener, FetchResponseMsg, NetworkError};
@@ -326,7 +326,6 @@ impl HTMLImageElement {
             cors_setting_for_element(self.upcast()),
             sender,
             UsePlaceholder::Yes,
-            CanRequestImages::Yes,
         );
 
         match cache_result {
@@ -1107,7 +1106,6 @@ impl HTMLImageElement {
             cors_setting_for_element(self.upcast()),
             sender,
             UsePlaceholder::No,
-            CanRequestImages::Yes,
         );
 
         match cache_result {
diff --git a/components/script/dom/htmlvideoelement.rs b/components/script/dom/htmlvideoelement.rs
index a890b49af72..c06dc083a22 100644
--- a/components/script/dom/htmlvideoelement.rs
+++ b/components/script/dom/htmlvideoelement.rs
@@ -27,8 +27,8 @@ use html5ever::{LocalName, Prefix};
 use ipc_channel::ipc;
 use ipc_channel::router::ROUTER;
 use net_traits::image_cache::{
-    CanRequestImages, ImageCache, ImageCacheResult, ImageOrMetadataAvailable, ImageResponse,
-    PendingImageId, UsePlaceholder,
+    ImageCache, ImageCacheResult, ImageOrMetadataAvailable, ImageResponse, PendingImageId,
+    UsePlaceholder,
 };
 use net_traits::request::{CredentialsMode, Destination, RequestBuilder};
 use net_traits::{
@@ -163,7 +163,6 @@ impl HTMLVideoElement {
             None,
             sender,
             UsePlaceholder::No,
-            CanRequestImages::Yes,
         );
 
         match cache_result {
diff --git a/components/script/dom/testbinding.rs b/components/script/dom/testbinding.rs
index 1ac5d8db31a..37c13c173e3 100644
--- a/components/script/dom/testbinding.rs
+++ b/components/script/dom/testbinding.rs
@@ -1054,8 +1054,8 @@ impl TestBindingMethods for TestBinding {
         }
     }
 
-    fn AdvanceClock(&self, ms: i32, tick: bool) {
-        self.global().as_window().advance_animation_clock(ms, tick);
+    fn AdvanceClock(&self, ms: i32) {
+        self.global().as_window().advance_animation_clock(ms);
     }
 
     fn Panic(&self) {
diff --git a/components/script/dom/webidls/TestBinding.webidl b/components/script/dom/webidls/TestBinding.webidl
index 6aa748e502f..482e5a3ea7e 100644
--- a/components/script/dom/webidls/TestBinding.webidl
+++ b/components/script/dom/webidls/TestBinding.webidl
@@ -517,7 +517,7 @@ interface TestBinding {
   [Pref="dom.testbinding.prefcontrolled.enabled"]
   const unsigned short prefControlledConstDisabled = 0;
   [Pref="layout.animations.test.enabled"]
-  void advanceClock(long millis, optional boolean forceLayoutTick = true);
+  void advanceClock(long millis);
 
   [Pref="dom.testbinding.prefcontrolled2.enabled"]
   readonly attribute boolean prefControlledAttributeEnabled;
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 93019cf913d..481586a71ae 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -173,6 +173,8 @@ pub enum ReflowReason {
     IFrameLoadEvent,
     MissingExplicitReflow,
     ElementStateChanged,
+    TickAnimations,
+    AdvanceClock(i32),
 }
 
 #[dom_struct]
@@ -1544,16 +1546,16 @@ impl Window {
         )
     }
 
-    /// Advances the layout animation clock by `delta` milliseconds, and then
-    /// forces a reflow if `tick` is true.
-    pub fn advance_animation_clock(&self, delta: i32, tick: bool) {
-        self.layout_chan
-            .send(Msg::AdvanceClockMs(
-                delta,
-                tick,
-                self.origin().immutable().clone(),
-            ))
-            .unwrap();
+    /// Prepares to tick animations and then does a reflow which also advances the
+    /// layout animation clock.
+    pub fn advance_animation_clock(&self, delta: i32) {
+        let pipeline_id = self.upcast::<GlobalScope>().pipeline_id();
+        ScriptThread::restyle_animating_nodes_for_advancing_clock(&pipeline_id);
+        self.force_reflow(
+            ReflowGoal::TickAnimations,
+            ReflowReason::AdvanceClock(delta),
+            None,
+        );
     }
 
     /// Reflows the page unconditionally if possible and not suppressed. This
@@ -1626,11 +1628,15 @@ impl Window {
 
         // If this reflow is for display, ensure webgl canvases are composited with
         // up-to-date contents.
-        match reflow_goal {
-            ReflowGoal::Full => document.flush_dirty_canvases(),
-            ReflowGoal::TickAnimations | ReflowGoal::LayoutQuery(..) => {},
+        if for_display {
+            document.flush_dirty_canvases();
         }
 
+        let advance_clock_delta = match reason {
+            ReflowReason::AdvanceClock(delta) => Some(delta),
+            _ => None,
+        };
+
         // Send new document and relevant styles to layout.
         let needs_display = reflow_goal.needs_display();
         let reflow = ScriptReflow {
@@ -1645,6 +1651,7 @@ impl Window {
             script_join_chan: join_chan,
             dom_count: document.dom_count(),
             pending_restyles: document.drain_pending_restyles(),
+            advance_clock_delta,
         };
 
         self.layout_chan
@@ -2487,6 +2494,8 @@ fn debug_reflow_events(id: PipelineId, reflow_goal: &ReflowGoal, reason: &Reflow
         ReflowReason::IFrameLoadEvent => "\tIFrameLoadEvent",
         ReflowReason::MissingExplicitReflow => "\tMissingExplicitReflow",
         ReflowReason::ElementStateChanged => "\tElementStateChanged",
+        ReflowReason::TickAnimations => "\tTickAnimations",
+        ReflowReason::AdvanceClock(..) => "\tAdvanceClock",
     });
 
     println!("{}", debug_msg);
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 165e526fa76..5a99d800799 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -136,12 +136,12 @@ use script_traits::CompositorEvent::{
     WheelEvent,
 };
 use script_traits::{
-    CompositorEvent, ConstellationControlMsg, DiscardBrowsingContext, DocumentActivity,
-    EventResult, HistoryEntryReplacement, InitialScriptState, JsEvalResult, LayoutMsg, LoadData,
-    LoadOrigin, MediaSessionActionType, MouseButton, MouseEventType, NewLayoutInfo, Painter,
-    ProgressiveWebMetricType, ScriptMsg, ScriptThreadFactory, ScriptToConstellationChan,
-    StructuredSerializedData, TimerSchedulerMsg, TouchEventType, TouchId,
-    TransitionOrAnimationEventType, UntrustedNodeAddress, UpdatePipelineIdReason,
+    AnimationTickType, CompositorEvent, ConstellationControlMsg, DiscardBrowsingContext,
+    DocumentActivity, EventResult, HistoryEntryReplacement, InitialScriptState, JsEvalResult,
+    LayoutMsg, LoadData, LoadOrigin, MediaSessionActionType, MouseButton, MouseEventType,
+    NewLayoutInfo, Painter, ProgressiveWebMetricType, ScriptMsg, ScriptThreadFactory,
+    ScriptToConstellationChan, StructuredSerializedData, TimerSchedulerMsg, TouchEventType,
+    TouchId, TransitionOrAnimationEventType, UntrustedNodeAddress, UpdatePipelineIdReason,
     WebrenderIpcSender, WheelDelta, WindowSizeData, WindowSizeType,
 };
 use servo_atoms::Atom;
@@ -1497,7 +1497,7 @@ impl ScriptThread {
                         self.handle_set_scroll_state(id, &scroll_state);
                     })
                 },
-                FromConstellation(ConstellationControlMsg::TickAllAnimations(pipeline_id)) => {
+                FromConstellation(ConstellationControlMsg::TickAllAnimations(pipeline_id, _)) => {
                     // step 7.8
                     if !animation_ticks.contains(&pipeline_id) {
                         animation_ticks.insert(pipeline_id);
@@ -1703,7 +1703,7 @@ impl ScriptThread {
                 RemoveHistoryStates(id, ..) => Some(id),
                 FocusIFrame(id, ..) => Some(id),
                 WebDriverScriptCommand(id, ..) => Some(id),
-                TickAllAnimations(id) => Some(id),
+                TickAllAnimations(id, ..) => Some(id),
                 TransitionOrAnimationEvent { .. } => None,
                 WebFontLoaded(id) => Some(id),
                 DispatchIFrameLoadEvent {
@@ -1902,8 +1902,8 @@ impl ScriptThread {
             ConstellationControlMsg::WebDriverScriptCommand(pipeline_id, msg) => {
                 self.handle_webdriver_msg(pipeline_id, msg)
             },
-            ConstellationControlMsg::TickAllAnimations(pipeline_id) => {
-                self.handle_tick_all_animations(pipeline_id)
+            ConstellationControlMsg::TickAllAnimations(pipeline_id, tick_type) => {
+                self.handle_tick_all_animations(pipeline_id, tick_type)
             },
             ConstellationControlMsg::TransitionOrAnimationEvent {
                 pipeline_id,
@@ -2914,13 +2914,45 @@ impl ScriptThread {
         debug!("Exited script thread.");
     }
 
+    fn restyle_animating_nodes(&self, id: &PipelineId) -> bool {
+        match self.animating_nodes.borrow().get(id) {
+            Some(nodes) => {
+                for node in nodes.iter() {
+                    node.dirty(NodeDamage::NodeStyleDamaged);
+                }
+                true
+            },
+            None => false,
+        }
+    }
+
+    pub fn restyle_animating_nodes_for_advancing_clock(id: &PipelineId) {
+        SCRIPT_THREAD_ROOT.with(|root| {
+            let script_thread = unsafe { &*root.get().unwrap() };
+            script_thread.restyle_animating_nodes(id);
+        });
+    }
+
     /// Handles when layout thread finishes all animation in one tick
-    fn handle_tick_all_animations(&self, id: PipelineId) {
+    fn handle_tick_all_animations(&self, id: PipelineId, tick_type: AnimationTickType) {
         let document = match self.documents.borrow().find_document(id) {
             Some(document) => document,
             None => return warn!("Message sent to closed pipeline {}.", id),
         };
-        document.run_the_animation_frame_callbacks();
+        if tick_type.contains(AnimationTickType::REQUEST_ANIMATION_FRAME) {
+            document.run_the_animation_frame_callbacks();
+        }
+        if tick_type.contains(AnimationTickType::CSS_ANIMATIONS_AND_TRANSITIONS) {
+            if !self.restyle_animating_nodes(&id) {
+                return;
+            }
+
+            document.window().force_reflow(
+                ReflowGoal::TickAnimations,
+                ReflowReason::TickAnimations,
+                None,
+            );
+        }
     }
 
     /// Handles firing of transition-related events.
@@ -2969,11 +3001,6 @@ impl ScriptThread {
             }
         }
 
-        // Not quite the right thing - see #13865.
-        if event_type.finalizes_transition_or_animation() {
-            node.dirty(NodeDamage::NodeStyleDamaged);
-        }
-
         let event_atom = match event_type {
             TransitionOrAnimationEventType::AnimationEnd => atom!("animationend"),
             TransitionOrAnimationEventType::TransitionCancel => atom!("transitioncancel"),
diff --git a/components/script_layout_interface/message.rs b/components/script_layout_interface/message.rs
index fe117436b51..f42304ed5b5 100644
--- a/components/script_layout_interface/message.rs
+++ b/components/script_layout_interface/message.rs
@@ -47,15 +47,6 @@ pub enum Msg {
     /// Get an RPC interface.
     GetRPC(Sender<Box<dyn LayoutRPC + Send>>),
 
-    /// Requests that the layout thread render the next frame of all animations.
-    TickAnimations(ImmutableOrigin),
-
-    /// Updates layout's timer for animation testing from script.
-    ///
-    /// The inner field is the number of *milliseconds* to advance, and the bool
-    /// field is whether animations should be force-ticked.
-    AdvanceClockMs(i32, bool, ImmutableOrigin),
-
     /// Requests that the layout thread measure its memory usage. The resulting reports are sent back
     /// via the supplied channel.
     CollectReports(ReportsChan),
@@ -216,6 +207,8 @@ pub struct ScriptReflow {
     pub origin: ImmutableOrigin,
     /// Restyle snapshot map.
     pub pending_restyles: Vec<(TrustedNodeAddress, PendingRestyle)>,
+    /// How much to advance the clock when testing.
+    pub advance_clock_delta: Option<i32>,
 }
 
 pub struct LayoutThreadInit {
diff --git a/components/script_traits/Cargo.toml b/components/script_traits/Cargo.toml
index e5800e374c4..74e04d03161 100644
--- a/components/script_traits/Cargo.toml
+++ b/components/script_traits/Cargo.toml
@@ -11,6 +11,7 @@ name = "script_traits"
 path = "lib.rs"
 
 [dependencies]
+bitflags = "1.0"
 bluetooth_traits = {path = "../bluetooth_traits"}
 canvas_traits = {path = "../canvas_traits"}
 cookie = "0.11"
diff --git a/components/script_traits/lib.rs b/components/script_traits/lib.rs
index c23221f929f..caa3cf2d34a 100644
--- a/components/script_traits/lib.rs
+++ b/components/script_traits/lib.rs
@@ -9,6 +9,8 @@
 #![deny(missing_docs)]
 #![deny(unsafe_code)]
 
+#[macro_use]
+extern crate bitflags;
 #[macro_use]
 extern crate malloc_size_of;
 #[macro_use]
@@ -122,8 +124,6 @@ pub enum LayoutControlMsg {
     ExitNow,
     /// Requests the current epoch (layout counter) from this layout.
     GetCurrentEpoch(IpcSender<Epoch>),
-    /// Asks layout to run another step in its animation.
-    TickAnimations(ImmutableOrigin),
     /// Tells layout about the new scrolling offsets of each scrollable stacking context.
     SetScrollStates(Vec<ScrollState>),
     /// Requests the current load state of Web fonts. `true` is returned if fonts are still loading
@@ -403,7 +403,7 @@ pub enum ConstellationControlMsg {
     /// Passes a webdriver command to the script thread for execution
     WebDriverScriptCommand(PipelineId, WebDriverScriptCommand),
     /// Notifies script thread that all animations are done
-    TickAllAnimations(PipelineId),
+    TickAllAnimations(PipelineId, AnimationTickType),
     /// Notifies the script thread that a transition or animation related event should be sent.
     TransitionOrAnimationEvent {
         /// The pipeline id of the layout task that sent this message.
@@ -812,13 +812,15 @@ pub struct IFrameLoadInfoWithData {
     pub window_size: WindowSizeData,
 }
 
-/// Specifies whether the script or layout thread needs to be ticked for animation.
-#[derive(Debug, Deserialize, Serialize)]
-pub enum AnimationTickType {
-    /// The script thread.
-    Script,
-    /// The layout thread.
-    Layout,
+bitflags! {
+    #[derive(Deserialize, Serialize)]
+    /// Specifies if rAF should be triggered and/or CSS Animations and Transitions.
+    pub struct AnimationTickType: u8 {
+        /// Trigger a call to requestAnimationFrame.
+        const REQUEST_ANIMATION_FRAME = 0b001;
+        /// Trigger restyles for CSS Animations and Transitions.
+        const CSS_ANIMATIONS_AND_TRANSITIONS = 0b010;
+    }
 }
 
 /// The scroll state of a stacking context.
diff --git a/components/style/animation.rs b/components/style/animation.rs
index eed3aaada1a..cde31dc2b3a 100644
--- a/components/style/animation.rs
+++ b/components/style/animation.rs
@@ -18,7 +18,6 @@ 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;
 use crate::values::computed::Time;
 use crate::values::computed::TimingFunction;
 use crate::values::generics::box_::AnimationIterationCount;
@@ -77,30 +76,33 @@ pub struct KeyframesAnimationState {
 }
 
 impl KeyframesAnimationState {
-    /// Performs a tick in the animation state, i.e., increments the counter of
-    /// the current iteration count, updates times and then toggles the
-    /// direction if appropriate.
-    ///
-    /// Returns true if the animation should keep running.
-    pub fn tick(&mut self) -> bool {
-        debug!("KeyframesAnimationState::tick");
-        self.started_at += self.duration + self.delay;
+    /// Given the current time, advances this animation to the next iteration,
+    /// updates times, and then toggles the direction if appropriate. Otherwise
+    /// does nothing.
+    pub fn iterate_if_necessary(&mut self, time: f64) {
+        if !self.iteration_over(time) {
+            return;
+        }
+
         match self.running_state {
-            // If it's paused, don't update direction or iteration count.
-            KeyframesRunningState::Paused(_) => return true,
+            KeyframesRunningState::Paused(_) => return,
             KeyframesRunningState::Running => {},
         }
 
-        if let KeyframesIterationState::Finite(ref mut current, ref max) = self.iteration_state {
-            *current += 1.0;
+        if let KeyframesIterationState::Finite(ref mut current, max) = self.iteration_state {
+            // If we are already on the final iteration, just exit now.
             // NB: This prevent us from updating the direction, which might be
             // needed for the correct handling of animation-fill-mode.
-            if *current >= *max {
-                return false;
+            if (max - *current) <= 1.0 {
+                return;
             }
+
+            *current += 1.0;
         }
 
         // Update the next iteration direction if applicable.
+        // TODO(mrobinson): The duration might now be wrong for floating point iteration counts.
+        self.started_at += self.duration + self.delay;
         match self.direction {
             AnimationDirection::Alternate | AnimationDirection::AlternateReverse => {
                 self.current_direction = match self.current_direction {
@@ -111,8 +113,29 @@ impl KeyframesAnimationState {
             },
             _ => {},
         }
+    }
 
-        true
+    fn iteration_over(&self, time: f64) -> bool {
+        time > (self.started_at + self.duration)
+    }
+
+    fn has_ended(&self, time: f64) -> bool {
+        if !self.iteration_over(time) {
+            return false;
+        }
+
+        // If we are paused then we haven't ended.
+        match self.running_state {
+            KeyframesRunningState::Paused(_) => return false,
+            KeyframesRunningState::Running => {},
+        }
+
+        // If we have a limited number of iterations and we cannot advance to another
+        // iteration, then we have ended.
+        return match self.iteration_state {
+            KeyframesIterationState::Finite(current, max) if (max - current) <= 1.0 => true,
+            KeyframesIterationState::Finite(..) | KeyframesIterationState::Infinite => false,
+        };
     }
 
     /// Updates the appropiate state from other animation.
@@ -122,7 +145,7 @@ impl KeyframesAnimationState {
     ///
     /// There are some bits of state we can't just replace, over all taking in
     /// account times, so here's that logic.
-    pub fn update_from_other(&mut self, other: &Self, timer: &Timer) {
+    pub fn update_from_other(&mut self, other: &Self, now: f64) {
         use self::KeyframesRunningState::*;
 
         debug!(
@@ -148,12 +171,10 @@ impl KeyframesAnimationState {
         //
         // If we're pausing the animation, compute the progress value.
         match (&mut self.running_state, old_running_state) {
-            (&mut Running, Paused(progress)) => {
-                new_started_at = timer.seconds() - (self.duration * progress)
-            },
+            (&mut Running, Paused(progress)) => new_started_at = now - (self.duration * progress),
             (&mut Paused(ref mut new), Paused(old)) => *new = old,
             (&mut Paused(ref mut progress), Running) => {
-                *progress = (timer.seconds() - old_started_at) / old_duration
+                *progress = (now - old_started_at) / old_duration
             },
             _ => {},
         }
@@ -239,6 +260,18 @@ impl Animation {
         }
     }
 
+    /// Whether or not this animation has ended at the provided time. This does
+    /// not take into account canceling i.e. when an animation or transition is
+    /// canceled due to changes in the style.
+    pub fn has_ended(&self, time: f64) -> bool {
+        match *self {
+            Animation::Transition(_, started_at, ref property_animation) => {
+                time >= started_at + (property_animation.duration)
+            },
+            Animation::Keyframes(_, _, _, ref state) => state.has_ended(time),
+        }
+    }
+
     /// Whether this animation has the same end value as another one.
     #[inline]
     fn is_transition_with_same_end_value(&self, other_animation: &PropertyAnimation) -> bool {
@@ -463,52 +496,26 @@ impl ElementAnimationState {
         false
     }
 
-    pub(crate) fn apply_completed_animations(&mut self, style: &mut Arc<ComputedValues>) {
-        for animation in self.finished_animations.iter() {
-            // TODO: Make this a bit more general and add support animation-fill-mode.
-            // Without support for that property though, animations that have ended should
-            // not affect property values. This is why we only process transitions here.
-            if let Animation::Transition(_, _, property_animation) = animation {
-                property_animation.update(Arc::make_mut(style), 1.0);
+    pub(crate) fn apply_new_and_running_animations<E>(
+        &mut self,
+        context: &SharedStyleContext,
+        style: &mut Arc<ComputedValues>,
+        font_metrics: &dyn crate::font_metrics::FontMetricsProvider,
+    ) where
+        E: TElement,
+    {
+        if !self.running_animations.is_empty() {
+            let style = Arc::make_mut(style);
+            for animation in self.running_animations.iter_mut() {
+                update_style_for_animation::<E>(context, animation, style, font_metrics);
             }
         }
-    }
 
-    pub(crate) fn apply_running_animations<E>(
-        &mut self,
-        context: &SharedStyleContext,
-        style: &mut Arc<ComputedValues>,
-        font_metrics: &dyn crate::font_metrics::FontMetricsProvider,
-    ) where
-        E: TElement,
-    {
-        // Return early so that we don't unnecessarily clone the style when making it mutable.
-        if self.running_animations.is_empty() {
-            return;
-        }
-
-        let style = Arc::make_mut(style);
-        for animation in self.running_animations.iter_mut() {
-            update_style_for_animation::<E>(context, animation, style, font_metrics);
-        }
-    }
-
-    pub(crate) fn apply_new_animations<E>(
-        &mut self,
-        context: &SharedStyleContext,
-        style: &mut Arc<ComputedValues>,
-        font_metrics: &dyn crate::font_metrics::FontMetricsProvider,
-    ) where
-        E: TElement,
-    {
-        // Return early so that we don't unnecessarily clone the style when making it mutable.
-        if self.new_animations.is_empty() {
-            return;
-        }
-
-        let style = Arc::make_mut(style);
-        for animation in self.new_animations.iter_mut() {
-            update_style_for_animation::<E>(context, animation, style, font_metrics);
+        if !self.new_animations.is_empty() {
+            let style = Arc::make_mut(style);
+            for animation in self.new_animations.iter_mut() {
+                update_style_for_animation::<E>(context, animation, style, font_metrics);
+            }
         }
     }
 
@@ -525,24 +532,6 @@ impl ElementAnimationState {
         self.new_animations.push(animation);
     }
 
-    fn add_or_update_new_animation(&mut self, timer: &Timer, new_animation: Animation) {
-        // If the animation was already present in the list for the node,
-        // just update its state.
-        if let Animation::Keyframes(_, _, ref new_name, ref new_state) = new_animation {
-            for existing_animation in self.running_animations.iter_mut() {
-                match existing_animation {
-                    Animation::Keyframes(_, _, ref name, ref mut state) if *name == *new_name => {
-                        state.update_from_other(&new_state, timer);
-                        return;
-                    },
-                    _ => {},
-                }
-            }
-        }
-        // Otherwise just add the new running animation.
-        self.add_new_animation(new_animation);
-    }
-
     /// Update our animations given a new style, canceling or starting new animations
     /// when appropriate.
     pub fn update_animations_for_new_style<E>(
@@ -572,33 +561,61 @@ impl ElementAnimationState {
         }
 
         maybe_start_animations(element, &context, &new_style, self);
+
+        self.iterate_running_animations_if_necessary(context.current_time_for_animations);
     }
 
     /// Update our transitions given a new style, canceling or starting new animations
     /// when appropriate.
-    pub fn update_transitions_for_new_style(
+    pub fn update_transitions_for_new_style<E>(
         &mut self,
         context: &SharedStyleContext,
         opaque_node: OpaqueNode,
-        before_change_style: Option<&Arc<ComputedValues>>,
-        new_style: &Arc<ComputedValues>,
-    ) {
+        old_style: Option<&Arc<ComputedValues>>,
+        after_change_style: &Arc<ComputedValues>,
+        font_metrics: &dyn crate::font_metrics::FontMetricsProvider,
+    ) where
+        E: TElement,
+    {
         // If this is the first style, we don't trigger any transitions and we assume
         // there were no previously triggered transitions.
-        let before_change_style = match before_change_style {
-            Some(before_change_style) => before_change_style,
+        let mut before_change_style = match old_style {
+            Some(old_style) => Arc::clone(old_style),
             None => return,
         };
 
+        // We convert old values into `before-change-style` here.
+        // See https://drafts.csswg.org/css-transitions/#starting. We need to clone the
+        // style because this might still be a reference to the original `old_style` and
+        // we want to preserve that so that we can later properly calculate restyle damage.
+        if self.running_animations.is_empty() || self.new_animations.is_empty() {
+            before_change_style = before_change_style.clone();
+            self.apply_new_and_running_animations::<E>(
+                context,
+                &mut before_change_style,
+                font_metrics,
+            );
+        }
+
         let transitioning_properties = start_transitions_if_applicable(
             context,
             opaque_node,
-            before_change_style,
-            new_style,
+            &before_change_style,
+            after_change_style,
             self,
         );
         self.cancel_transitions_with_nontransitioning_properties(&transitioning_properties);
     }
+
+    /// When necessary, iterate our running animations to the next iteration.
+    pub fn iterate_running_animations_if_necessary(&mut self, time: f64) {
+        for animation in self.running_animations.iter_mut() {
+            match *animation {
+                Animation::Keyframes(_, _, _, ref mut state) => state.iterate_if_necessary(time),
+                _ => {},
+            }
+        }
+    }
 }
 
 /// Kick off any new transitions for this node and return all of the properties that are
@@ -651,8 +668,8 @@ pub fn start_transitions_if_applicable(
         // Kick off the animation.
         debug!("Kicking off transition of {:?}", property_animation);
         let box_style = new_style.get_box();
-        let now = context.timer.seconds();
-        let start_time = now + (box_style.transition_delay_mod(transition.index).seconds() as f64);
+        let start_time = context.current_time_for_animations +
+            (box_style.transition_delay_mod(transition.index).seconds() as f64);
         animation_state.add_new_animation(Animation::Transition(
             opaque_node,
             start_time,
@@ -755,8 +772,7 @@ pub fn maybe_start_animations<E>(
         }
 
         let delay = box_style.animation_delay_mod(i).seconds();
-        let now = context.timer.seconds();
-        let animation_start = now + delay as f64;
+        let animation_start = context.current_time_for_animations + delay as f64;
         let iteration_state = match box_style.animation_iteration_count_mod(i) {
             AnimationIterationCount::Infinite => KeyframesIterationState::Infinite,
             AnimationIterationCount::Number(n) => KeyframesIterationState::Finite(0.0, n),
@@ -778,24 +794,36 @@ pub fn maybe_start_animations<E>(
             AnimationPlayState::Running => KeyframesRunningState::Running,
         };
 
-        animation_state.add_or_update_new_animation(
-            &context.timer,
-            Animation::Keyframes(
-                element.as_node().opaque(),
-                anim.clone(),
-                name.clone(),
-                KeyframesAnimationState {
-                    started_at: animation_start,
-                    duration: duration as f64,
-                    delay: delay as f64,
-                    iteration_state,
-                    running_state,
-                    direction: animation_direction,
-                    current_direction: initial_direction,
-                    cascade_style: new_style.clone(),
-                },
-            ),
-        );
+        let new_state = KeyframesAnimationState {
+            started_at: animation_start,
+            duration: duration as f64,
+            delay: delay as f64,
+            iteration_state,
+            running_state,
+            direction: animation_direction,
+            current_direction: initial_direction,
+            cascade_style: new_style.clone(),
+        };
+
+        // If the animation was already present in the list for the node, just update its state.
+        for existing_animation in animation_state.running_animations.iter_mut() {
+            match existing_animation {
+                Animation::Keyframes(_, _, ref old_name, ref mut old_state)
+                    if *old_name == *name =>
+                {
+                    old_state.update_from_other(&new_state, context.current_time_for_animations);
+                    return;
+                }
+                _ => {},
+            }
+        }
+
+        animation_state.add_new_animation(Animation::Keyframes(
+            element.as_node().opaque(),
+            anim.clone(),
+            name.clone(),
+            new_state,
+        ));
     }
 }
 
@@ -811,7 +839,7 @@ pub fn update_style_for_animation<E>(
     debug!("update_style_for_animation: {:?}", animation);
     match *animation {
         Animation::Transition(_, start_time, ref property_animation) => {
-            let now = context.timer.seconds();
+            let now = context.current_time_for_animations;
             let progress = (now - start_time) / (property_animation.duration);
             let progress = progress.min(1.0);
             if progress >= 0.0 {
@@ -823,7 +851,7 @@ pub fn update_style_for_animation<E>(
             let started_at = state.started_at;
 
             let now = match state.running_state {
-                KeyframesRunningState::Running => context.timer.seconds(),
+                KeyframesRunningState::Running => context.current_time_for_animations,
                 KeyframesRunningState::Paused(progress) => started_at + duration * progress,
             };
 
diff --git a/components/style/context.rs b/components/style/context.rs
index 5bcae3e6738..03b16ab5171 100644
--- a/components/style/context.rs
+++ b/components/style/context.rs
@@ -25,7 +25,6 @@ use crate::shared_lock::StylesheetGuards;
 use crate::sharing::StyleSharingCache;
 use crate::stylist::Stylist;
 use crate::thread_state::{self, ThreadState};
-use crate::timer::Timer;
 use crate::traversal::DomTraversal;
 use crate::traversal_flags::TraversalFlags;
 use app_units::Au;
@@ -156,9 +155,9 @@ pub struct SharedStyleContext<'a> {
     /// Guards for pre-acquired locks
     pub guards: StylesheetGuards<'a>,
 
-    /// The current timer for transitions and animations. This is needed to test
-    /// them.
-    pub timer: Timer,
+    /// The current time for transitions and animations. This is needed to ensure
+    /// a consistent sampling time and also to adjust the time for testing.
+    pub current_time_for_animations: f64,
 
     /// Flags controlling how we traverse the tree.
     pub traversal_flags: TraversalFlags,
diff --git a/components/style/matching.rs b/components/style/matching.rs
index 23d396cdd4b..02a7fcfe76f 100644
--- a/components/style/matching.rs
+++ b/components/style/matching.rs
@@ -442,31 +442,17 @@ trait PrivateMatchMethods: TElement {
         let mut animation_states = shared_context.animation_states.write();
         let mut animation_state = animation_states.remove(&this_opaque).unwrap_or_default();
 
-        if let Some(ref mut old_values) = *old_values {
-            // We convert old values into `before-change-style` here.
-            // https://drafts.csswg.org/css-transitions/#starting
-            animation_state.apply_completed_animations(old_values);
-            animation_state.apply_running_animations::<Self>(
-                shared_context,
-                old_values,
-                &context.thread_local.font_metrics_provider,
-            );
-        }
-
         animation_state.update_animations_for_new_style(*self, &shared_context, &new_values);
-        animation_state.update_transitions_for_new_style(
+
+        animation_state.update_transitions_for_new_style::<Self>(
             &shared_context,
             this_opaque,
             old_values.as_ref(),
             new_values,
-        );
-
-        animation_state.apply_running_animations::<Self>(
-            shared_context,
-            new_values,
             &context.thread_local.font_metrics_provider,
         );
-        animation_state.apply_new_animations::<Self>(
+
+        animation_state.apply_new_and_running_animations::<Self>(
             shared_context,
             new_values,
             &context.thread_local.font_metrics_provider,
diff --git a/tests/wpt/metadata/css/css-transitions/animations/text-shadow-interpolation.html.ini b/tests/wpt/metadata/css/css-transitions/animations/text-shadow-interpolation.html.ini
index 46d05d6844b..2f854bb55e3 100644
--- a/tests/wpt/metadata/css/css-transitions/animations/text-shadow-interpolation.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/animations/text-shadow-interpolation.html.ini
@@ -89,9 +89,6 @@
   [Web Animations: property <text-shadow> from neutral to [green 20px 20px 20px\] at (-0.3) should be [rgb(255, 176, 0) 7px 33px 7px\]]
     expected: FAIL
 
-  [CSS Animations: property <text-shadow> from neutral to [green 20px 20px 20px\] at (0.3) should be [rgb(179, 154, 0) 13px 27px 13px\]]
-    expected: FAIL
-
   [Web Animations: property <text-shadow> from neutral to [green 20px 20px 20px\] at (0) should be [rgb(255, 165, 0) 10px 30px 10px\]]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/css/css-transitions/animations/vertical-align-interpolation.html.ini b/tests/wpt/metadata/css/css-transitions/animations/vertical-align-interpolation.html.ini
index 3cfce27e151..2fa4f4f6dd4 100644
--- a/tests/wpt/metadata/css/css-transitions/animations/vertical-align-interpolation.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/animations/vertical-align-interpolation.html.ini
@@ -209,21 +209,3 @@
   [CSS Animations: property <vertical-align> from [inherit\] to [40px\] at (1.5) should be [10px\]]
     expected: FAIL
 
-  [CSS Transitions with transition: all: property <vertical-align> from [0px\] to [100px\] at (0.6) should be [60px\]]
-    expected: FAIL
-
-  [CSS Transitions with transition: all: property <vertical-align> from [0px\] to [100px\] at (-0.5) should be [-50px\]]
-    expected: FAIL
-
-  [CSS Transitions: property <vertical-align> from [0px\] to [100px\] at (0.6) should be [60px\]]
-    expected: FAIL
-
-  [CSS Transitions: property <vertical-align> from [0px\] to [100px\] at (-0.5) should be [-50px\]]
-    expected: FAIL
-
-  [CSS Transitions with transition: all: property <vertical-align> from [0px\] to [100px\] at (0.3) should be [30px\]]
-    expected: FAIL
-
-  [CSS Transitions: property <vertical-align> from [0px\] to [100px\] at (0.3) should be [30px\]]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-transitions/disconnected-element-001.html.ini b/tests/wpt/metadata/css/css-transitions/disconnected-element-001.html.ini
index 2eee391a749..cd98f4d3d67 100644
--- a/tests/wpt/metadata/css/css-transitions/disconnected-element-001.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/disconnected-element-001.html.ini
@@ -3,9 +3,6 @@
   [Transitions are canceled when an element is re-parented to the same node]
     expected: NOTRUN
 
-  [Transitions are canceled when an element is removed from the document]
+  [Transitions are canceled when an element is re-parented]
     expected: TIMEOUT
 
-  [Transitions are canceled when an element is re-parented]
-    expected: NOTRUN
-
diff --git a/tests/wpt/metadata/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini b/tests/wpt/metadata/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini
deleted file mode 100644
index 70a00a101f6..00000000000
--- a/tests/wpt/metadata/css/css-transitions/no-transition-from-ua-to-blocking-stylesheet.html.ini
+++ /dev/null
@@ -1,2 +0,0 @@
-[no-transition-from-ua-to-blocking-stylesheet.html]
-  expected: FAIL
diff --git a/tests/wpt/metadata/css/css-transitions/properties-value-001.html.ini b/tests/wpt/metadata/css/css-transitions/properties-value-001.html.ini
index d96df7a0f92..9ca3c31e0af 100644
--- a/tests/wpt/metadata/css/css-transitions/properties-value-001.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/properties-value-001.html.ini
@@ -53,459 +53,3 @@
   [background-position length(px) / events]
     expected: FAIL
 
-  [outline-width length(px) / values]
-    expected: FAIL
-
-  [border-left-width length(em) / values]
-    expected: FAIL
-
-  [border-bottom-width length(px) / values]
-    expected: FAIL
-
-  [border-top-width length(em) / values]
-    expected: FAIL
-
-  [line-height number(decimal) / values]
-    expected: FAIL
-
-  [word-spacing length(mm) / values]
-    expected: FAIL
-
-  [text-indent length(pc) / values]
-    expected: FAIL
-
-  [opacity number[0,1\](zero-to-one) / values]
-    expected: FAIL
-
-  [line-height number(integer) / values]
-    expected: FAIL
-
-  [outline-offset length(px) / values]
-    expected: FAIL
-
-  [font-size length(pt) / values]
-    expected: FAIL
-
-  [max-height length(px) / values]
-    expected: FAIL
-
-  [vertical-align length(in) / values]
-    expected: FAIL
-
-  [max-height percentage(%) / values]
-    expected: FAIL
-
-  [min-width length(px) / values]
-    expected: FAIL
-
-  [border-top-color color(rgba) / values]
-    expected: FAIL
-
-  [border-right-color color(rgba) / values]
-    expected: FAIL
-
-  [font-size length(ex) / values]
-    expected: FAIL
-
-  [min-height length(pc) / values]
-    expected: FAIL
-
-  [line-height length(px) / values]
-    expected: FAIL
-
-  [word-spacing length(px) / values]
-    expected: FAIL
-
-  [vertical-align percentage(%) / values]
-    expected: FAIL
-
-  [border-right-width length(pc) / values]
-    expected: FAIL
-
-  [line-height length(ex) / values]
-    expected: FAIL
-
-  [color color(rgba) / values]
-    expected: FAIL
-
-  [font-size length(in) / values]
-    expected: FAIL
-
-  [font-size length(em) / values]
-    expected: FAIL
-
-  [border-left-width length(mm) / values]
-    expected: FAIL
-
-  [vertical-align length(em) / values]
-    expected: FAIL
-
-  [clip rectangle(rectangle) / values]
-    expected: FAIL
-
-  [word-spacing length(em) / values]
-    expected: FAIL
-
-  [border-right-width length(ex) / values]
-    expected: FAIL
-
-  [border-top-width length(cm) / values]
-    expected: FAIL
-
-  [max-width length(em) / values]
-    expected: FAIL
-
-  [font-size length(cm) / values]
-    expected: FAIL
-
-  [border-right-width length(cm) / values]
-    expected: FAIL
-
-  [outline-offset length(ex) / values]
-    expected: FAIL
-
-  [min-width length(cm) / values]
-    expected: FAIL
-
-  [min-height length(px) / values]
-    expected: FAIL
-
-  [min-width length(mm) / values]
-    expected: FAIL
-
-  [border-bottom-width length(in) / values]
-    expected: FAIL
-
-  [vertical-align length(pc) / values]
-    expected: FAIL
-
-  [vertical-align length(cm) / values]
-    expected: FAIL
-
-  [max-height length(ex) / values]
-    expected: FAIL
-
-  [vertical-align length(ex) / values]
-    expected: FAIL
-
-  [min-height percentage(%) / values]
-    expected: FAIL
-
-  [max-height length(pt) / values]
-    expected: FAIL
-
-  [outline-offset length(mm) / values]
-    expected: FAIL
-
-  [font-weight font-weight(keyword) / values]
-    expected: FAIL
-
-  [max-height length(mm) / values]
-    expected: FAIL
-
-  [outline-offset length(pt) / values]
-    expected: FAIL
-
-  [line-height length(mm) / values]
-    expected: FAIL
-
-  [line-height length(cm) / values]
-    expected: FAIL
-
-  [border-top-width length(mm) / values]
-    expected: FAIL
-
-  [letter-spacing length(in) / values]
-    expected: FAIL
-
-  [border-bottom-color color(rgba) / values]
-    expected: FAIL
-
-  [min-width percentage(%) / values]
-    expected: FAIL
-
-  [min-height length(cm) / values]
-    expected: FAIL
-
-  [letter-spacing length(mm) / values]
-    expected: FAIL
-
-  [font-size percentage(%) / values]
-    expected: FAIL
-
-  [letter-spacing length(cm) / values]
-    expected: FAIL
-
-  [vertical-align length(pt) / values]
-    expected: FAIL
-
-  [border-left-color color(rgba) / values]
-    expected: FAIL
-
-  [letter-spacing length(pc) / values]
-    expected: FAIL
-
-  [letter-spacing length(pt) / values]
-    expected: FAIL
-
-  [word-spacing length(ex) / values]
-    expected: FAIL
-
-  [line-height length(pt) / values]
-    expected: FAIL
-
-  [border-top-width length(px) / values]
-    expected: FAIL
-
-  [min-width length(pt) / values]
-    expected: FAIL
-
-  [border-bottom-width length(mm) / values]
-    expected: FAIL
-
-  [border-bottom-width length(cm) / values]
-    expected: FAIL
-
-  [min-width length(em) / values]
-    expected: FAIL
-
-  [min-height length(em) / values]
-    expected: FAIL
-
-  [max-width length(mm) / values]
-    expected: FAIL
-
-  [min-height length(ex) / values]
-    expected: FAIL
-
-  [max-width length(px) / values]
-    expected: FAIL
-
-  [font-size length(mm) / values]
-    expected: FAIL
-
-  [min-width length(pc) / values]
-    expected: FAIL
-
-  [letter-spacing length(em) / values]
-    expected: FAIL
-
-  [line-height length(em) / values]
-    expected: FAIL
-
-  [border-bottom-width length(pt) / values]
-    expected: FAIL
-
-  [word-spacing length(pc) / values]
-    expected: FAIL
-
-  [outline-offset length(in) / values]
-    expected: FAIL
-
-  [word-spacing length(in) / values]
-    expected: FAIL
-
-  [outline-width length(pt) / values]
-    expected: FAIL
-
-  [border-top-width length(pc) / values]
-    expected: FAIL
-
-  [border-left-width length(px) / values]
-    expected: FAIL
-
-  [font-size length(px) / values]
-    expected: FAIL
-
-  [border-left-width length(cm) / values]
-    expected: FAIL
-
-  [border-right-width length(px) / values]
-    expected: FAIL
-
-  [outline-width length(in) / values]
-    expected: FAIL
-
-  [word-spacing length(pt) / values]
-    expected: FAIL
-
-  [border-right-width length(mm) / values]
-    expected: FAIL
-
-  [max-width length(in) / values]
-    expected: FAIL
-
-  [outline-color color(rgba) / values]
-    expected: FAIL
-
-  [text-indent length(pt) / values]
-    expected: FAIL
-
-  [border-right-width length(pt) / values]
-    expected: FAIL
-
-  [border-left-width length(in) / values]
-    expected: FAIL
-
-  [max-height length(in) / values]
-    expected: FAIL
-
-  [line-height length(in) / values]
-    expected: FAIL
-
-  [border-bottom-width length(em) / values]
-    expected: FAIL
-
-  [outline-width length(ex) / values]
-    expected: FAIL
-
-  [font-size length(pc) / values]
-    expected: FAIL
-
-  [min-width length(in) / values]
-    expected: FAIL
-
-  [outline-width length(cm) / values]
-    expected: FAIL
-
-  [max-width percentage(%) / values]
-    expected: FAIL
-
-  [max-width length(ex) / values]
-    expected: FAIL
-
-  [letter-spacing length(ex) / values]
-    expected: FAIL
-
-  [border-left-width length(ex) / values]
-    expected: FAIL
-
-  [outline-width length(mm) / values]
-    expected: FAIL
-
-  [border-left-width length(pc) / values]
-    expected: FAIL
-
-  [outline-width length(pc) / values]
-    expected: FAIL
-
-  [word-spacing percentage(%) / values]
-    expected: FAIL
-
-  [font-weight font-weight(numeric) / values]
-    expected: FAIL
-
-  [vertical-align length(px) / values]
-    expected: FAIL
-
-  [letter-spacing length(px) / values]
-    expected: FAIL
-
-  [max-width length(pt) / values]
-    expected: FAIL
-
-  [line-height percentage(%) / values]
-    expected: FAIL
-
-  [border-top-width length(pt) / values]
-    expected: FAIL
-
-  [min-height length(mm) / values]
-    expected: FAIL
-
-  [max-height length(cm) / values]
-    expected: FAIL
-
-  [outline-width length(em) / values]
-    expected: FAIL
-
-  [border-right-width length(em) / values]
-    expected: FAIL
-
-  [max-height length(em) / values]
-    expected: FAIL
-
-  [max-width length(cm) / values]
-    expected: FAIL
-
-  [outline-offset length(em) / values]
-    expected: FAIL
-
-  [outline-offset length(cm) / values]
-    expected: FAIL
-
-  [border-top-width length(ex) / values]
-    expected: FAIL
-
-  [border-right-width length(in) / values]
-    expected: FAIL
-
-  [z-index integer(integer) / values]
-    expected: FAIL
-
-  [border-left-width length(pt) / values]
-    expected: FAIL
-
-  [vertical-align length(mm) / values]
-    expected: FAIL
-
-  [border-bottom-width length(pc) / values]
-    expected: FAIL
-
-  [line-height length(pc) / values]
-    expected: FAIL
-
-  [border-top-width length(in) / values]
-    expected: FAIL
-
-  [border-bottom-width length(ex) / values]
-    expected: FAIL
-
-  [min-height length(in) / values]
-    expected: FAIL
-
-  [outline-offset length(pc) / values]
-    expected: FAIL
-
-  [max-height length(pc) / values]
-    expected: FAIL
-
-  [background-color color(rgba) / values]
-    expected: FAIL
-
-  [min-height length(pt) / values]
-    expected: FAIL
-
-  [word-spacing length(cm) / values]
-    expected: FAIL
-
-  [max-width length(pc) / values]
-    expected: FAIL
-
-  [min-width length(ex) / values]
-    expected: FAIL
-
-  [text-indent length(ex) / values]
-    expected: FAIL
-
-  [text-indent length(px) / values]
-    expected: FAIL
-
-  [text-indent length(mm) / values]
-    expected: FAIL
-
-  [text-indent length(cm) / values]
-    expected: FAIL
-
-  [text-shadow shadow(shadow) / values]
-    expected: FAIL
-
-  [text-indent length(in) / values]
-    expected: FAIL
-
-  [text-indent length(em) / values]
-    expected: FAIL
-
-  [text-indent percentage(%) / values]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-transitions/properties-value-003.html.ini b/tests/wpt/metadata/css/css-transitions/properties-value-003.html.ini
index 96f9c486148..4a6754aa23a 100644
--- a/tests/wpt/metadata/css/css-transitions/properties-value-003.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/properties-value-003.html.ini
@@ -461,45 +461,12 @@
   [background-image image(data) / values]
     expected: FAIL
 
-  [transform transform(rotate) / values]
-    expected: FAIL
-
-  [border-bottom-right-radius border-radius(px-px) / values]
-    expected: FAIL
-
   [background-image image(gradient) / values]
     expected: FAIL
 
-  [font-stretch font-stretch(keyword) / values]
-    expected: FAIL
-
-  [border-top-right-radius border-radius(px) / values]
-    expected: FAIL
-
-  [border-top-left-radius border-radius(px-px) / values]
-    expected: FAIL
-
-  [border-bottom-right-radius border-radius(px) / values]
-    expected: FAIL
-
-  [border-bottom-left-radius border-radius(px-px) / values]
-    expected: FAIL
-
   [background-image image(url) / values]
     expected: FAIL
 
-  [border-top-left-radius border-radius(px) / values]
-    expected: FAIL
-
-  [border-bottom-left-radius border-radius(px) / values]
-    expected: FAIL
-
-  [box-shadow box-shadow(shadow) / values]
-    expected: FAIL
-
-  [border-top-right-radius border-radius(px-px) / values]
-    expected: FAIL
-
   [display display(static to absolute) / events]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/css/css-transitions/properties-value-implicit-001.html.ini b/tests/wpt/metadata/css/css-transitions/properties-value-implicit-001.html.ini
index 0f90b844a61..c06f494a4a0 100644
--- a/tests/wpt/metadata/css/css-transitions/properties-value-implicit-001.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/properties-value-implicit-001.html.ini
@@ -5,48 +5,6 @@
   [background-position length-em(em) / values]
     expected: FAIL
 
-  [border-top-width length-em(em) / values]
-    expected: FAIL
-
-  [max-width length-em(em) / values]
-    expected: FAIL
-
-  [line-height length-em(em) / values]
-    expected: FAIL
-
-  [vertical-align length-em(em) / values]
-    expected: FAIL
-
-  [min-height length-em(em) / values]
-    expected: FAIL
-
-  [border-left-width length-em(em) / values]
-    expected: FAIL
-
-  [word-spacing length-em(em) / values]
-    expected: FAIL
-
-  [outline-width length-em(em) / values]
-    expected: FAIL
-
-  [letter-spacing length-em(em) / values]
-    expected: FAIL
-
-  [max-height length-em(em) / values]
-    expected: FAIL
-
-  [min-width length-em(em) / values]
-    expected: FAIL
-
-  [text-indent length-em(em) / values]
-    expected: FAIL
-
-  [outline-offset length-em(em) / values]
-    expected: FAIL
-
-  [border-right-width length-em(em) / values]
-    expected: FAIL
-
-  [border-bottom-width length-em(em) / values]
+  [top length-em(em) / values]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/css/css-transitions/properties-value-inherit-001.html.ini b/tests/wpt/metadata/css/css-transitions/properties-value-inherit-001.html.ini
index 5d20389c8e9..937da3b3013 100644
--- a/tests/wpt/metadata/css/css-transitions/properties-value-inherit-001.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/properties-value-inherit-001.html.ini
@@ -56,3 +56,813 @@
   [background-position length(px) / events]
     expected: FAIL
 
+  [top length(pt) / events]
+    expected: FAIL
+
+  [border-right-width length(mm) / events]
+    expected: FAIL
+
+  [width length(pt) / events]
+    expected: FAIL
+
+  [border-bottom-width length(pc) / events]
+    expected: FAIL
+
+  [height length(ex) / events]
+    expected: FAIL
+
+  [padding-bottom length(mm) / events]
+    expected: FAIL
+
+  [letter-spacing length(em) / events]
+    expected: FAIL
+
+  [letter-spacing length(ex) / events]
+    expected: FAIL
+
+  [border-top-width length(px) / events]
+    expected: FAIL
+
+  [border-top-width length(pt) / events]
+    expected: FAIL
+
+  [padding-top length(em) / events]
+    expected: FAIL
+
+  [letter-spacing length(mm) / events]
+    expected: FAIL
+
+  [line-height length(in) / events]
+    expected: FAIL
+
+  [font-size percentage(%) / events]
+    expected: FAIL
+
+  [outline-width length(pc) / events]
+    expected: FAIL
+
+  [text-indent percentage(%) / events]
+    expected: FAIL
+
+  [max-width length(in) / events]
+    expected: FAIL
+
+  [margin-top length(cm) / events]
+    expected: FAIL
+
+  [margin-right length(pt) / events]
+    expected: FAIL
+
+  [right length(ex) / events]
+    expected: FAIL
+
+  [vertical-align length(px) / events]
+    expected: FAIL
+
+  [max-height length(em) / events]
+    expected: FAIL
+
+  [width length(ex) / events]
+    expected: FAIL
+
+  [border-bottom-color color(rgba) / events]
+    expected: FAIL
+
+  [width percentage(%) / events]
+    expected: FAIL
+
+  [margin-top length(ex) / events]
+    expected: FAIL
+
+  [border-top-width length(in) / events]
+    expected: FAIL
+
+  [right length(em) / events]
+    expected: FAIL
+
+  [top length(ex) / events]
+    expected: FAIL
+
+  [text-shadow shadow(shadow) / events]
+    expected: FAIL
+
+  [padding-left length(px) / events]
+    expected: FAIL
+
+  [margin-top length(em) / events]
+    expected: FAIL
+
+  [left length(em) / events]
+    expected: FAIL
+
+  [margin-left length(px) / events]
+    expected: FAIL
+
+  [max-height percentage(%) / events]
+    expected: FAIL
+
+  [bottom length(ex) / events]
+    expected: FAIL
+
+  [padding-left length(mm) / events]
+    expected: FAIL
+
+  [right length(mm) / events]
+    expected: FAIL
+
+  [margin-top length(pc) / events]
+    expected: FAIL
+
+  [border-left-width length(pt) / events]
+    expected: FAIL
+
+  [outline-offset length(mm) / events]
+    expected: FAIL
+
+  [vertical-align length(in) / events]
+    expected: FAIL
+
+  [border-bottom-width length(pt) / events]
+    expected: FAIL
+
+  [letter-spacing length(cm) / events]
+    expected: FAIL
+
+  [border-bottom-width length(in) / events]
+    expected: FAIL
+
+  [margin-bottom length(pc) / events]
+    expected: FAIL
+
+  [border-left-width length(mm) / events]
+    expected: FAIL
+
+  [height length(em) / events]
+    expected: FAIL
+
+  [letter-spacing length(px) / events]
+    expected: FAIL
+
+  [height length(cm) / events]
+    expected: FAIL
+
+  [padding-top length(in) / events]
+    expected: FAIL
+
+  [text-indent length(mm) / events]
+    expected: FAIL
+
+  [max-width length(ex) / events]
+    expected: FAIL
+
+  [padding-top length(px) / events]
+    expected: FAIL
+
+  [border-top-width length(pc) / events]
+    expected: FAIL
+
+  [top length(cm) / events]
+    expected: FAIL
+
+  [left length(ex) / events]
+    expected: FAIL
+
+  [min-width length(ex) / events]
+    expected: FAIL
+
+  [left length(pc) / events]
+    expected: FAIL
+
+  [font-size length(px) / events]
+    expected: FAIL
+
+  [vertical-align length(em) / events]
+    expected: FAIL
+
+  [left length(in) / events]
+    expected: FAIL
+
+  [left length(px) / events]
+    expected: FAIL
+
+  [border-bottom-width length(mm) / events]
+    expected: FAIL
+
+  [min-width length(cm) / events]
+    expected: FAIL
+
+  [vertical-align length(cm) / events]
+    expected: FAIL
+
+  [text-indent length(ex) / events]
+    expected: FAIL
+
+  [padding-bottom length(px) / events]
+    expected: FAIL
+
+  [line-height length(em) / events]
+    expected: FAIL
+
+  [max-width percentage(%) / events]
+    expected: FAIL
+
+  [outline-offset length(cm) / events]
+    expected: FAIL
+
+  [top length(in) / events]
+    expected: FAIL
+
+  [border-left-color color(rgba) / events]
+    expected: FAIL
+
+  [margin-left length(mm) / events]
+    expected: FAIL
+
+  [margin-top length(pt) / events]
+    expected: FAIL
+
+  [min-height length(cm) / events]
+    expected: FAIL
+
+  [max-height length(cm) / events]
+    expected: FAIL
+
+  [width length(mm) / events]
+    expected: FAIL
+
+  [width length(pc) / events]
+    expected: FAIL
+
+  [font-size length(pt) / events]
+    expected: FAIL
+
+  [font-size length(in) / events]
+    expected: FAIL
+
+  [vertical-align length(mm) / events]
+    expected: FAIL
+
+  [height length(px) / events]
+    expected: FAIL
+
+  [right percentage(%) / events]
+    expected: FAIL
+
+  [border-top-color color(rgba) / events]
+    expected: FAIL
+
+  [outline-offset length(em) / events]
+    expected: FAIL
+
+  [padding-right length(px) / events]
+    expected: FAIL
+
+  [vertical-align length(ex) / events]
+    expected: FAIL
+
+  [outline-width length(em) / events]
+    expected: FAIL
+
+  [width length(cm) / events]
+    expected: FAIL
+
+  [margin-right length(ex) / events]
+    expected: FAIL
+
+  [text-indent length(in) / events]
+    expected: FAIL
+
+  [border-right-width length(cm) / events]
+    expected: FAIL
+
+  [margin-right length(em) / events]
+    expected: FAIL
+
+  [letter-spacing length(in) / events]
+    expected: FAIL
+
+  [border-left-width length(ex) / events]
+    expected: FAIL
+
+  [min-width length(mm) / events]
+    expected: FAIL
+
+  [letter-spacing length(pc) / events]
+    expected: FAIL
+
+  [margin-right length(pc) / events]
+    expected: FAIL
+
+  [margin-left length(pt) / events]
+    expected: FAIL
+
+  [border-right-width length(pc) / events]
+    expected: FAIL
+
+  [height length(in) / events]
+    expected: FAIL
+
+  [border-left-width length(in) / events]
+    expected: FAIL
+
+  [min-height length(ex) / events]
+    expected: FAIL
+
+  [text-indent length(pc) / events]
+    expected: FAIL
+
+  [text-indent length(em) / events]
+    expected: FAIL
+
+  [bottom length(em) / events]
+    expected: FAIL
+
+  [border-right-color color(rgba) / events]
+    expected: FAIL
+
+  [font-size length(pc) / events]
+    expected: FAIL
+
+  [line-height length(pc) / events]
+    expected: FAIL
+
+  [right length(in) / events]
+    expected: FAIL
+
+  [padding-top length(pt) / events]
+    expected: FAIL
+
+  [min-width length(em) / events]
+    expected: FAIL
+
+  [border-right-width length(pt) / events]
+    expected: FAIL
+
+  [opacity number[0,1\](zero-to-one) / events]
+    expected: FAIL
+
+  [padding-bottom length(cm) / events]
+    expected: FAIL
+
+  [margin-right length(in) / events]
+    expected: FAIL
+
+  [margin-top length(px) / events]
+    expected: FAIL
+
+  [padding-top length(ex) / events]
+    expected: FAIL
+
+  [margin-left length(ex) / events]
+    expected: FAIL
+
+  [text-indent length(px) / events]
+    expected: FAIL
+
+  [text-indent length(cm) / events]
+    expected: FAIL
+
+  [top length(px) / events]
+    expected: FAIL
+
+  [bottom length(cm) / events]
+    expected: FAIL
+
+  [border-bottom-width length(px) / events]
+    expected: FAIL
+
+  [margin-bottom length(ex) / events]
+    expected: FAIL
+
+  [font-weight font-weight(keyword) / events]
+    expected: FAIL
+
+  [font-weight font-weight(numeric) / events]
+    expected: FAIL
+
+  [max-width length(mm) / events]
+    expected: FAIL
+
+  [line-height length(mm) / events]
+    expected: FAIL
+
+  [height percentage(%) / events]
+    expected: FAIL
+
+  [border-right-width length(px) / events]
+    expected: FAIL
+
+  [border-top-width length(mm) / events]
+    expected: FAIL
+
+  [line-height length(cm) / events]
+    expected: FAIL
+
+  [word-spacing length(pt) / events]
+    expected: FAIL
+
+  [border-left-width length(em) / events]
+    expected: FAIL
+
+  [max-width length(pc) / events]
+    expected: FAIL
+
+  [padding-bottom length(em) / events]
+    expected: FAIL
+
+  [min-width length(pt) / events]
+    expected: FAIL
+
+  [outline-width length(cm) / events]
+    expected: FAIL
+
+  [border-right-width length(in) / events]
+    expected: FAIL
+
+  [bottom length(in) / events]
+    expected: FAIL
+
+  [padding-right length(mm) / events]
+    expected: FAIL
+
+  [line-height length(pt) / events]
+    expected: FAIL
+
+  [border-left-width length(px) / events]
+    expected: FAIL
+
+  [left length(cm) / events]
+    expected: FAIL
+
+  [word-spacing length(ex) / events]
+    expected: FAIL
+
+  [margin-right length(px) / events]
+    expected: FAIL
+
+  [clip rectangle(rectangle) / events]
+    expected: FAIL
+
+  [color color(rgba) / events]
+    expected: FAIL
+
+  [margin-left length(cm) / events]
+    expected: FAIL
+
+  [background-color color(rgba) / events]
+    expected: FAIL
+
+  [min-width length(in) / events]
+    expected: FAIL
+
+  [word-spacing percentage(%) / events]
+    expected: FAIL
+
+  [padding-right length(cm) / events]
+    expected: FAIL
+
+  [width length(em) / events]
+    expected: FAIL
+
+  [line-height percentage(%) / events]
+    expected: FAIL
+
+  [margin-left length(em) / events]
+    expected: FAIL
+
+  [margin-right length(cm) / events]
+    expected: FAIL
+
+  [border-bottom-width length(cm) / events]
+    expected: FAIL
+
+  [bottom length(pc) / events]
+    expected: FAIL
+
+  [text-indent length(pt) / events]
+    expected: FAIL
+
+  [top percentage(%) / events]
+    expected: FAIL
+
+  [padding-left length(pt) / events]
+    expected: FAIL
+
+  [min-width percentage(%) / events]
+    expected: FAIL
+
+  [right length(px) / events]
+    expected: FAIL
+
+  [padding-right length(in) / events]
+    expected: FAIL
+
+  [left length(mm) / events]
+    expected: FAIL
+
+  [line-height length(ex) / events]
+    expected: FAIL
+
+  [bottom length(px) / events]
+    expected: FAIL
+
+  [line-height number(integer) / events]
+    expected: FAIL
+
+  [padding-left length(pc) / events]
+    expected: FAIL
+
+  [outline-width length(ex) / events]
+    expected: FAIL
+
+  [padding-left length(cm) / events]
+    expected: FAIL
+
+  [left length(pt) / events]
+    expected: FAIL
+
+  [outline-width length(mm) / events]
+    expected: FAIL
+
+  [padding-left length(ex) / events]
+    expected: FAIL
+
+  [word-spacing length(cm) / events]
+    expected: FAIL
+
+  [font-size length(mm) / events]
+    expected: FAIL
+
+  [margin-bottom length(cm) / events]
+    expected: FAIL
+
+  [word-spacing length(mm) / events]
+    expected: FAIL
+
+  [max-width length(pt) / events]
+    expected: FAIL
+
+  [border-right-width length(em) / events]
+    expected: FAIL
+
+  [font-size length(cm) / events]
+    expected: FAIL
+
+  [margin-left length(in) / events]
+    expected: FAIL
+
+  [top length(em) / events]
+    expected: FAIL
+
+  [padding-right length(pt) / events]
+    expected: FAIL
+
+  [padding-top length(pc) / events]
+    expected: FAIL
+
+  [border-top-width length(ex) / events]
+    expected: FAIL
+
+  [min-height length(pt) / events]
+    expected: FAIL
+
+  [width length(in) / events]
+    expected: FAIL
+
+  [min-width length(pc) / events]
+    expected: FAIL
+
+  [margin-bottom length(mm) / events]
+    expected: FAIL
+
+  [height length(pc) / events]
+    expected: FAIL
+
+  [max-width length(px) / events]
+    expected: FAIL
+
+  [bottom length(pt) / events]
+    expected: FAIL
+
+  [padding-right length(ex) / events]
+    expected: FAIL
+
+  [border-top-width length(em) / events]
+    expected: FAIL
+
+  [max-height length(pt) / events]
+    expected: FAIL
+
+  [vertical-align percentage(%) / events]
+    expected: FAIL
+
+  [word-spacing length(em) / events]
+    expected: FAIL
+
+  [margin-left length(pc) / events]
+    expected: FAIL
+
+  [min-height percentage(%) / events]
+    expected: FAIL
+
+  [padding-bottom length(ex) / events]
+    expected: FAIL
+
+  [line-height number(decimal) / events]
+    expected: FAIL
+
+  [padding-left length(em) / events]
+    expected: FAIL
+
+  [letter-spacing length(pt) / events]
+    expected: FAIL
+
+  [bottom percentage(%) / events]
+    expected: FAIL
+
+  [min-height length(pc) / events]
+    expected: FAIL
+
+  [border-left-width length(pc) / events]
+    expected: FAIL
+
+  [margin-bottom length(in) / events]
+    expected: FAIL
+
+  [outline-width length(pt) / events]
+    expected: FAIL
+
+  [margin-bottom length(em) / events]
+    expected: FAIL
+
+  [top length(mm) / events]
+    expected: FAIL
+
+  [outline-color color(rgba) / events]
+    expected: FAIL
+
+  [bottom length(mm) / events]
+    expected: FAIL
+
+  [padding-top length(mm) / events]
+    expected: FAIL
+
+  [border-right-width length(ex) / events]
+    expected: FAIL
+
+  [border-top-width length(cm) / events]
+    expected: FAIL
+
+  [outline-width length(in) / events]
+    expected: FAIL
+
+  [right length(pt) / events]
+    expected: FAIL
+
+  [width length(px) / events]
+    expected: FAIL
+
+  [height length(pt) / events]
+    expected: FAIL
+
+  [word-spacing length(in) / events]
+    expected: FAIL
+
+  [padding-left length(in) / events]
+    expected: FAIL
+
+  [min-height length(em) / events]
+    expected: FAIL
+
+  [left percentage(%) / events]
+    expected: FAIL
+
+  [word-spacing length(px) / events]
+    expected: FAIL
+
+  [padding-bottom length(pc) / events]
+    expected: FAIL
+
+  [max-height length(ex) / events]
+    expected: FAIL
+
+  [border-left-width length(cm) / events]
+    expected: FAIL
+
+  [outline-offset length(ex) / events]
+    expected: FAIL
+
+  [max-height length(pc) / events]
+    expected: FAIL
+
+  [padding-right length(pc) / events]
+    expected: FAIL
+
+  [top length(pc) / events]
+    expected: FAIL
+
+  [vertical-align length(pc) / events]
+    expected: FAIL
+
+  [min-height length(px) / events]
+    expected: FAIL
+
+  [margin-right length(mm) / events]
+    expected: FAIL
+
+  [max-height length(mm) / events]
+    expected: FAIL
+
+  [right length(pc) / events]
+    expected: FAIL
+
+  [line-height length(px) / events]
+    expected: FAIL
+
+  [word-spacing length(pc) / events]
+    expected: FAIL
+
+  [vertical-align length(pt) / events]
+    expected: FAIL
+
+  [padding-top length(cm) / events]
+    expected: FAIL
+
+  [font-size length(em) / events]
+    expected: FAIL
+
+  [right length(cm) / events]
+    expected: FAIL
+
+  [outline-offset length(pt) / events]
+    expected: FAIL
+
+  [font-size length(ex) / events]
+    expected: FAIL
+
+  [min-height length(in) / events]
+    expected: FAIL
+
+  [max-width length(cm) / events]
+    expected: FAIL
+
+  [border-bottom-width length(ex) / events]
+    expected: FAIL
+
+  [max-height length(px) / events]
+    expected: FAIL
+
+  [min-width length(px) / events]
+    expected: FAIL
+
+  [outline-offset length(px) / events]
+    expected: FAIL
+
+  [margin-top length(in) / events]
+    expected: FAIL
+
+  [outline-offset length(in) / events]
+    expected: FAIL
+
+  [margin-bottom length(pt) / events]
+    expected: FAIL
+
+  [max-width length(em) / events]
+    expected: FAIL
+
+  [padding-bottom length(pt) / events]
+    expected: FAIL
+
+  [min-height length(mm) / events]
+    expected: FAIL
+
+  [padding-bottom length(in) / events]
+    expected: FAIL
+
+  [margin-bottom length(px) / events]
+    expected: FAIL
+
+  [max-height length(in) / events]
+    expected: FAIL
+
+  [outline-width length(px) / events]
+    expected: FAIL
+
+  [padding-right length(em) / events]
+    expected: FAIL
+
+  [height length(mm) / events]
+    expected: FAIL
+
+  [margin-top length(mm) / events]
+    expected: FAIL
+
+  [outline-offset length(pc) / events]
+    expected: FAIL
+
+  [border-bottom-width length(em) / events]
+    expected: FAIL
+
+  [z-index integer(integer) / events]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/css-transitions/properties-value-inherit-002.html.ini b/tests/wpt/metadata/css/css-transitions/properties-value-inherit-002.html.ini
index 42f61e8ed49..5c36812ca0d 100644
--- a/tests/wpt/metadata/css/css-transitions/properties-value-inherit-002.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/properties-value-inherit-002.html.ini
@@ -53,459 +53,3 @@
   [background-position length(px) / events]
     expected: FAIL
 
-  [outline-width length(px) / values]
-    expected: FAIL
-
-  [border-bottom-width length(px) / values]
-    expected: FAIL
-
-  [border-top-width length(em) / values]
-    expected: FAIL
-
-  [line-height number(decimal) / values]
-    expected: FAIL
-
-  [opacity number[0,1\](zero-to-one) / values]
-    expected: FAIL
-
-  [line-height number(integer) / values]
-    expected: FAIL
-
-  [outline-offset length(px) / values]
-    expected: FAIL
-
-  [font-size length(pt) / values]
-    expected: FAIL
-
-  [max-height length(px) / values]
-    expected: FAIL
-
-  [vertical-align length(in) / values]
-    expected: FAIL
-
-  [max-height percentage(%) / values]
-    expected: FAIL
-
-  [min-width length(px) / values]
-    expected: FAIL
-
-  [font-size length(ex) / values]
-    expected: FAIL
-
-  [min-height length(pc) / values]
-    expected: FAIL
-
-  [line-height length(px) / values]
-    expected: FAIL
-
-  [word-spacing length(px) / values]
-    expected: FAIL
-
-  [vertical-align percentage(%) / values]
-    expected: FAIL
-
-  [border-right-width length(pc) / values]
-    expected: FAIL
-
-  [line-height length(ex) / values]
-    expected: FAIL
-
-  [color color(rgba) / values]
-    expected: FAIL
-
-  [font-size length(in) / values]
-    expected: FAIL
-
-  [font-size length(em) / values]
-    expected: FAIL
-
-  [vertical-align length(em) / values]
-    expected: FAIL
-
-  [clip rectangle(rectangle) / values]
-    expected: FAIL
-
-  [word-spacing length(em) / values]
-    expected: FAIL
-
-  [border-right-width length(ex) / values]
-    expected: FAIL
-
-  [border-top-width length(cm) / values]
-    expected: FAIL
-
-  [max-width length(em) / values]
-    expected: FAIL
-
-  [font-size length(cm) / values]
-    expected: FAIL
-
-  [border-right-width length(cm) / values]
-    expected: FAIL
-
-  [outline-offset length(ex) / values]
-    expected: FAIL
-
-  [min-width length(cm) / values]
-    expected: FAIL
-
-  [min-height length(px) / values]
-    expected: FAIL
-
-  [min-width length(mm) / values]
-    expected: FAIL
-
-  [border-bottom-width length(in) / values]
-    expected: FAIL
-
-  [vertical-align length(pc) / values]
-    expected: FAIL
-
-  [vertical-align length(cm) / values]
-    expected: FAIL
-
-  [max-height length(ex) / values]
-    expected: FAIL
-
-  [vertical-align length(ex) / values]
-    expected: FAIL
-
-  [min-height percentage(%) / values]
-    expected: FAIL
-
-  [max-height length(pt) / values]
-    expected: FAIL
-
-  [outline-offset length(mm) / values]
-    expected: FAIL
-
-  [font-weight font-weight(keyword) / values]
-    expected: FAIL
-
-  [max-height length(mm) / values]
-    expected: FAIL
-
-  [outline-offset length(pt) / values]
-    expected: FAIL
-
-  [line-height length(mm) / values]
-    expected: FAIL
-
-  [line-height length(cm) / values]
-    expected: FAIL
-
-  [border-top-width length(mm) / values]
-    expected: FAIL
-
-  [letter-spacing length(in) / values]
-    expected: FAIL
-
-  [min-width percentage(%) / values]
-    expected: FAIL
-
-  [min-height length(cm) / values]
-    expected: FAIL
-
-  [letter-spacing length(mm) / values]
-    expected: FAIL
-
-  [font-size percentage(%) / values]
-    expected: FAIL
-
-  [letter-spacing length(cm) / values]
-    expected: FAIL
-
-  [vertical-align length(pt) / values]
-    expected: FAIL
-
-  [letter-spacing length(pc) / values]
-    expected: FAIL
-
-  [letter-spacing length(pt) / values]
-    expected: FAIL
-
-  [word-spacing length(ex) / values]
-    expected: FAIL
-
-  [line-height length(pt) / values]
-    expected: FAIL
-
-  [border-top-width length(px) / values]
-    expected: FAIL
-
-  [min-width length(pt) / values]
-    expected: FAIL
-
-  [border-bottom-width length(mm) / values]
-    expected: FAIL
-
-  [border-bottom-width length(cm) / values]
-    expected: FAIL
-
-  [min-width length(em) / values]
-    expected: FAIL
-
-  [min-height length(em) / values]
-    expected: FAIL
-
-  [max-width length(mm) / values]
-    expected: FAIL
-
-  [min-height length(ex) / values]
-    expected: FAIL
-
-  [max-width length(px) / values]
-    expected: FAIL
-
-  [font-size length(mm) / values]
-    expected: FAIL
-
-  [min-width length(pc) / values]
-    expected: FAIL
-
-  [letter-spacing length(em) / values]
-    expected: FAIL
-
-  [line-height length(em) / values]
-    expected: FAIL
-
-  [border-bottom-width length(pt) / values]
-    expected: FAIL
-
-  [word-spacing length(pc) / values]
-    expected: FAIL
-
-  [outline-offset length(in) / values]
-    expected: FAIL
-
-  [outline-width length(pt) / values]
-    expected: FAIL
-
-  [border-top-width length(pc) / values]
-    expected: FAIL
-
-  [font-size length(px) / values]
-    expected: FAIL
-
-  [border-right-width length(px) / values]
-    expected: FAIL
-
-  [outline-width length(in) / values]
-    expected: FAIL
-
-  [word-spacing length(pt) / values]
-    expected: FAIL
-
-  [border-right-width length(mm) / values]
-    expected: FAIL
-
-  [max-width length(in) / values]
-    expected: FAIL
-
-  [outline-color color(rgba) / values]
-    expected: FAIL
-
-  [border-right-width length(pt) / values]
-    expected: FAIL
-
-  [max-height length(in) / values]
-    expected: FAIL
-
-  [line-height length(in) / values]
-    expected: FAIL
-
-  [border-bottom-width length(em) / values]
-    expected: FAIL
-
-  [outline-width length(ex) / values]
-    expected: FAIL
-
-  [font-size length(pc) / values]
-    expected: FAIL
-
-  [min-width length(in) / values]
-    expected: FAIL
-
-  [outline-width length(cm) / values]
-    expected: FAIL
-
-  [max-width percentage(%) / values]
-    expected: FAIL
-
-  [max-width length(ex) / values]
-    expected: FAIL
-
-  [letter-spacing length(ex) / values]
-    expected: FAIL
-
-  [outline-width length(mm) / values]
-    expected: FAIL
-
-  [outline-width length(pc) / values]
-    expected: FAIL
-
-  [font-weight font-weight(numeric) / values]
-    expected: FAIL
-
-  [vertical-align length(px) / values]
-    expected: FAIL
-
-  [letter-spacing length(px) / values]
-    expected: FAIL
-
-  [max-width length(pt) / values]
-    expected: FAIL
-
-  [line-height percentage(%) / values]
-    expected: FAIL
-
-  [border-top-width length(pt) / values]
-    expected: FAIL
-
-  [min-height length(mm) / values]
-    expected: FAIL
-
-  [max-height length(cm) / values]
-    expected: FAIL
-
-  [outline-width length(em) / values]
-    expected: FAIL
-
-  [border-right-width length(em) / values]
-    expected: FAIL
-
-  [max-height length(em) / values]
-    expected: FAIL
-
-  [max-width length(cm) / values]
-    expected: FAIL
-
-  [outline-offset length(em) / values]
-    expected: FAIL
-
-  [outline-offset length(cm) / values]
-    expected: FAIL
-
-  [border-top-width length(ex) / values]
-    expected: FAIL
-
-  [border-right-width length(in) / values]
-    expected: FAIL
-
-  [z-index integer(integer) / values]
-    expected: FAIL
-
-  [vertical-align length(mm) / values]
-    expected: FAIL
-
-  [border-bottom-width length(pc) / values]
-    expected: FAIL
-
-  [line-height length(pc) / values]
-    expected: FAIL
-
-  [border-top-width length(in) / values]
-    expected: FAIL
-
-  [border-bottom-width length(ex) / values]
-    expected: FAIL
-
-  [min-height length(in) / values]
-    expected: FAIL
-
-  [outline-offset length(pc) / values]
-    expected: FAIL
-
-  [max-height length(pc) / values]
-    expected: FAIL
-
-  [background-color color(rgba) / values]
-    expected: FAIL
-
-  [min-height length(pt) / values]
-    expected: FAIL
-
-  [max-width length(pc) / values]
-    expected: FAIL
-
-  [min-width length(ex) / values]
-    expected: FAIL
-
-  [word-spacing length(mm) / values]
-    expected: FAIL
-
-  [word-spacing length(in) / values]
-    expected: FAIL
-
-  [word-spacing length(cm) / values]
-    expected: FAIL
-
-  [text-indent length(pc) / values]
-    expected: FAIL
-
-  [text-indent length(ex) / values]
-    expected: FAIL
-
-  [text-indent length(px) / values]
-    expected: FAIL
-
-  [text-indent length(mm) / values]
-    expected: FAIL
-
-  [text-indent length(cm) / values]
-    expected: FAIL
-
-  [text-indent length(pt) / values]
-    expected: FAIL
-
-  [text-shadow shadow(shadow) / values]
-    expected: FAIL
-
-  [word-spacing percentage(%) / values]
-    expected: FAIL
-
-  [text-indent length(in) / values]
-    expected: FAIL
-
-  [text-indent length(em) / values]
-    expected: FAIL
-
-  [text-indent percentage(%) / values]
-    expected: FAIL
-
-  [border-left-width length(em) / values]
-    expected: FAIL
-
-  [border-top-color color(rgba) / values]
-    expected: FAIL
-
-  [border-right-color color(rgba) / values]
-    expected: FAIL
-
-  [border-left-width length(mm) / values]
-    expected: FAIL
-
-  [border-bottom-color color(rgba) / values]
-    expected: FAIL
-
-  [border-left-color color(rgba) / values]
-    expected: FAIL
-
-  [border-left-width length(px) / values]
-    expected: FAIL
-
-  [border-left-width length(cm) / values]
-    expected: FAIL
-
-  [border-left-width length(in) / values]
-    expected: FAIL
-
-  [border-left-width length(ex) / values]
-    expected: FAIL
-
-  [border-left-width length(pc) / values]
-    expected: FAIL
-
-  [border-left-width length(pt) / values]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-transitions/properties-value-inherit-003.html.ini b/tests/wpt/metadata/css/css-transitions/properties-value-inherit-003.html.ini
index 681c017a2ee..f2ba77c14c2 100644
--- a/tests/wpt/metadata/css/css-transitions/properties-value-inherit-003.html.ini
+++ b/tests/wpt/metadata/css/css-transitions/properties-value-inherit-003.html.ini
@@ -5,3 +5,90 @@
   [background-position length-em(em) / values]
     expected: FAIL
 
+  [line-height length-em(em) / events]
+    expected: FAIL
+
+  [padding-left length-em(em) / events]
+    expected: FAIL
+
+  [min-width length-em(em) / events]
+    expected: FAIL
+
+  [right length-em(em) / events]
+    expected: FAIL
+
+  [max-width length-em(em) / events]
+    expected: FAIL
+
+  [text-indent length-em(em) / events]
+    expected: FAIL
+
+  [margin-left length-em(em) / events]
+    expected: FAIL
+
+  [word-spacing length-em(em) / events]
+    expected: FAIL
+
+  [letter-spacing length-em(em) / events]
+    expected: FAIL
+
+  [width length-em(em) / events]
+    expected: FAIL
+
+  [padding-top length-em(em) / events]
+    expected: FAIL
+
+  [margin-right length-em(em) / events]
+    expected: FAIL
+
+  [max-height length-em(em) / events]
+    expected: FAIL
+
+  [padding-bottom length-em(em) / events]
+    expected: FAIL
+
+  [border-top-width length-em(em) / events]
+    expected: FAIL
+
+  [height length-em(em) / events]
+    expected: FAIL
+
+  [border-bottom-width length-em(em) / events]
+    expected: FAIL
+
+  [border-left-width length-em(em) / events]
+    expected: FAIL
+
+  [margin-bottom length-em(em) / events]
+    expected: FAIL
+
+  [min-height length-em(em) / events]
+    expected: FAIL
+
+  [outline-offset length-em(em) / events]
+    expected: FAIL
+
+  [padding-right length-em(em) / events]
+    expected: FAIL
+
+  [top length-em(em) / events]
+    expected: FAIL
+
+  [outline-width length-em(em) / events]
+    expected: FAIL
+
+  [bottom length-em(em) / events]
+    expected: FAIL
+
+  [vertical-align length-em(em) / events]
+    expected: FAIL
+
+  [left length-em(em) / events]
+    expected: FAIL
+
+  [margin-top length-em(em) / events]
+    expected: FAIL
+
+  [border-right-width length-em(em) / events]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/css/css-variables/variable-animation-substitute-into-keyframe-shorthand.html.ini b/tests/wpt/metadata/css/css-variables/variable-animation-substitute-into-keyframe-shorthand.html.ini
index 5d6b41c4332..454e1d2dec0 100644
--- a/tests/wpt/metadata/css/css-variables/variable-animation-substitute-into-keyframe-shorthand.html.ini
+++ b/tests/wpt/metadata/css/css-variables/variable-animation-substitute-into-keyframe-shorthand.html.ini
@@ -3,6 +3,3 @@
   [Verify border-bottom-color before animation]
     expected: FAIL
 
-  [Verify border-bottom-color after animation]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-variables/variable-animation-substitute-into-keyframe.html.ini b/tests/wpt/metadata/css/css-variables/variable-animation-substitute-into-keyframe.html.ini
index 225a08b98ac..f4720d8cf96 100644
--- a/tests/wpt/metadata/css/css-variables/variable-animation-substitute-into-keyframe.html.ini
+++ b/tests/wpt/metadata/css/css-variables/variable-animation-substitute-into-keyframe.html.ini
@@ -3,6 +3,3 @@
   [Verify color before animation]
     expected: FAIL
 
-  [Verify color after animation]
-    expected: FAIL
-
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index 76fedc21ad0..ae8e16e20bc 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -12871,7 +12871,7 @@
       ]
      ],
      "transition-raf.html": [
-      "6159bb9ab333544b4485d11025889ee94186c7eb",
+      "c38404503408e04b3c75b42df18ec3a7ec0819f5",
       [
        null,
        {}
diff --git a/tests/wpt/mozilla/meta/css/animations/basic-transition.html.ini b/tests/wpt/mozilla/meta/css/animations/basic-transition.html.ini
deleted file mode 100644
index 269b3cd3710..00000000000
--- a/tests/wpt/mozilla/meta/css/animations/basic-transition.html.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[basic-transition.html]
-  type: reftest
-  disabled: https://github.com/servo/servo/issues/13865
diff --git a/tests/wpt/mozilla/meta/css/animations/transition-raf.html.ini b/tests/wpt/mozilla/meta/css/animations/transition-raf.html.ini
deleted file mode 100644
index cfc207401ae..00000000000
--- a/tests/wpt/mozilla/meta/css/animations/transition-raf.html.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[transition-raf.html]
-  type: testharness
-  disabled: https://github.com/servo/servo/issues/13865
diff --git a/tests/wpt/mozilla/tests/css/animations/transition-raf.html b/tests/wpt/mozilla/tests/css/animations/transition-raf.html
index 6159bb9ab33..c3840450340 100644
--- a/tests/wpt/mozilla/tests/css/animations/transition-raf.html
+++ b/tests/wpt/mozilla/tests/css/animations/transition-raf.html
@@ -34,7 +34,7 @@ async_test(function(t) {
     assert_equals(getComputedStyle(box).getPropertyValue('width'), '100px');
     box.className = "expose";
     // Let the first restyle run at zero, then advance the clock.
-    setTimeout(function() { test.advanceClock(500, false) }, 0);
+    setTimeout(function() { test.advanceClock(500) }, 0);
   });
 }, "Transitions should work during RAF loop")
 </script>