Auto merge of #23456 - emilio:gecko-sync, r=emilio

style: Sync changes from mozilla-central.

See each individual commit for details.

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---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/23456)
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105 files changed, 1452 insertions, 2512 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 179e7109d5d..88bbbeca206 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4562,6 +4562,7 @@ dependencies = [
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "cssparser 0.25.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "euclid 0.19.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "malloc_size_of 0.0.1",
  "malloc_size_of_derive 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "selectors 0.21.0",
diff --git a/components/atoms/static_atoms.txt b/components/atoms/static_atoms.txt
index a42e998c958..c85d3563e75 100644
--- a/components/atoms/static_atoms.txt
+++ b/components/atoms/static_atoms.txt
@@ -30,6 +30,8 @@ error
 fantasy
 fetch
 file
+fill
+fill-opacity
 formdata
 fullscreenchange
 fullscreenerror
@@ -100,6 +102,8 @@ serif
 signalingstatechange
 srclang
 statechange
+stroke
+stroke-opacity
 storage
 submit
 suspend
diff --git a/components/layout/display_list/border.rs b/components/layout/display_list/border.rs
index dcbef4473fe..848386cb630 100644
--- a/components/layout/display_list/border.rs
+++ b/components/layout/display_list/border.rs
@@ -159,7 +159,7 @@ fn side_image_width(
     total_length: Au,
 ) -> f32 {
     match border_image_width {
-        BorderImageSideWidth::Length(v) => v.to_used_value(total_length).to_f32_px(),
+        BorderImageSideWidth::LengthPercentage(v) => v.to_used_value(total_length).to_f32_px(),
         BorderImageSideWidth::Number(x) => border_width * x.0,
         BorderImageSideWidth::Auto => border_width,
     }
diff --git a/components/layout/fragment.rs b/components/layout/fragment.rs
index ccc3de5ec7e..d3e9dbb6779 100644
--- a/components/layout/fragment.rs
+++ b/components/layout/fragment.rs
@@ -2793,7 +2793,7 @@ impl Fragment {
         let mut overflow = Overflow::from_rect(&border_box);
 
         // Box shadows cause us to draw outside our border box.
-        for box_shadow in &self.style().get_effects().box_shadow.0 {
+        for box_shadow in &*self.style().get_effects().box_shadow.0 {
             let offset = Vector2D::new(
                 Au::from(box_shadow.base.horizontal),
                 Au::from(box_shadow.base.vertical),
diff --git a/components/layout_thread/dom_wrapper.rs b/components/layout_thread/dom_wrapper.rs
index 301a7500713..d738ef1151f 100644
--- a/components/layout_thread/dom_wrapper.rs
+++ b/components/layout_thread/dom_wrapper.rs
@@ -888,6 +888,10 @@ impl<'le> ::selectors::Element for ServoLayoutElement<'le> {
         self.element.namespace()
     }
 
+    fn is_pseudo_element(&self) -> bool {
+        false
+    }
+
     fn match_pseudo_element(
         &self,
         _pseudo: &PseudoElement,
@@ -1394,6 +1398,10 @@ impl<'le> ::selectors::Element for ServoThreadSafeLayoutElement<'le> {
         ::selectors::OpaqueElement::new(unsafe { &*(self.as_node().opaque().0 as *const ()) })
     }
 
+    fn is_pseudo_element(&self) -> bool {
+        false
+    }
+
     fn parent_element(&self) -> Option<Self> {
         warn!("ServoThreadSafeLayoutElement::parent_element called");
         None
diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 1b918c0537b..c4174309af9 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -685,9 +685,9 @@ impl LayoutElementHelpers for LayoutDom<Element> {
         if let Some(url) = background {
             hints.push(from_declaration(
                 shared_lock,
-                PropertyDeclaration::BackgroundImage(background_image::SpecifiedValue(vec![
-                    Either::Second(specified::Image::for_cascade(url.into())),
-                ])),
+                PropertyDeclaration::BackgroundImage(background_image::SpecifiedValue(
+                    vec![Either::Second(specified::Image::for_cascade(url.into()))].into(),
+                )),
             ));
         }
 
@@ -2945,6 +2945,10 @@ impl<'a> SelectorsElement for DomRoot<Element> {
         }
     }
 
+    fn is_pseudo_element(&self) -> bool {
+        false
+    }
+
     fn match_pseudo_element(
         &self,
         _pseudo: &PseudoElement,
diff --git a/components/selectors/builder.rs b/components/selectors/builder.rs
index b548ceb83ce..c3e733cbeb0 100644
--- a/components/selectors/builder.rs
+++ b/components/selectors/builder.rs
@@ -84,12 +84,6 @@ impl<Impl: SelectorImpl> SelectorBuilder<Impl> {
         self.current_len = 0;
     }
 
-    /// Returns true if no simple selectors have ever been pushed to this builder.
-    #[inline(always)]
-    pub fn is_empty(&self) -> bool {
-        self.simple_selectors.is_empty()
-    }
-
     /// Returns true if combinators have ever been pushed to this builder.
     #[inline(always)]
     pub fn has_combinators(&self) -> bool {
diff --git a/components/selectors/matching.rs b/components/selectors/matching.rs
index aa200cc4b26..6554f2f9cc4 100644
--- a/components/selectors/matching.rs
+++ b/components/selectors/matching.rs
@@ -331,11 +331,9 @@ where
             return false;
         }
 
-        // Advance to the non-pseudo-element part of the selector, but let the
-        // context note that .
-        if iter.next_sequence().is_none() {
-            return true;
-        }
+        // Advance to the non-pseudo-element part of the selector.
+        let next_sequence = iter.next_sequence().unwrap();
+        debug_assert_eq!(next_sequence, Combinator::PseudoElement);
     }
 
     let result =
@@ -452,10 +450,6 @@ where
         },
         Combinator::Part => element.containing_shadow_host(),
         Combinator::SlotAssignment => {
-            debug_assert!(
-                context.current_host.is_some(),
-                "Should not be trying to match slotted rules in a non-shadow-tree context"
-            );
             debug_assert!(element
                 .assigned_slot()
                 .map_or(true, |s| s.is_html_slot_element()));
@@ -677,7 +671,6 @@ where
         Component::Slotted(ref selector) => {
             // <slots> are never flattened tree slottables.
             !element.is_html_slot_element() &&
-                element.assigned_slot().is_some() &&
                 context.shared.nest(|context| {
                     matches_complex_selector(selector.iter(), element, context, flags_setter)
                 })
diff --git a/components/selectors/parser.rs b/components/selectors/parser.rs
index a924bbc17d0..f049555730c 100644
--- a/components/selectors/parser.rs
+++ b/components/selectors/parser.rs
@@ -2002,9 +2002,7 @@ where
             },
             SimpleSelectorParseResult::SlottedPseudo(selector) => {
                 state.insert(SelectorParsingState::AFTER_SLOTTED);
-                if !builder.is_empty() {
-                    builder.push_combinator(Combinator::SlotAssignment);
-                }
+                builder.push_combinator(Combinator::SlotAssignment);
                 builder.push_simple_selector(Component::Slotted(selector));
             },
             SimpleSelectorParseResult::PseudoElement(p) => {
@@ -2012,9 +2010,7 @@ where
                 if !p.accepts_state_pseudo_classes() {
                     state.insert(SelectorParsingState::AFTER_NON_STATEFUL_PSEUDO_ELEMENT);
                 }
-                if !builder.is_empty() {
-                    builder.push_combinator(Combinator::PseudoElement);
-                }
+                builder.push_combinator(Combinator::PseudoElement);
                 builder.push_simple_selector(Component::PseudoElement(p));
             },
         }
@@ -2828,7 +2824,10 @@ pub mod tests {
         assert_eq!(
             parse("::before"),
             Ok(SelectorList::from_vec(vec![Selector::from_vec(
-                vec![Component::PseudoElement(PseudoElement::Before)],
+                vec![
+                    Component::Combinator(Combinator::PseudoElement),
+                    Component::PseudoElement(PseudoElement::Before),
+                ],
                 specificity(0, 0, 1) | HAS_PSEUDO_BIT,
             )]))
         );
@@ -2836,6 +2835,7 @@ pub mod tests {
             parse("::before:hover"),
             Ok(SelectorList::from_vec(vec![Selector::from_vec(
                 vec![
+                    Component::Combinator(Combinator::PseudoElement),
                     Component::PseudoElement(PseudoElement::Before),
                     Component::NonTSPseudoClass(PseudoClass::Hover),
                 ],
@@ -2846,6 +2846,7 @@ pub mod tests {
             parse("::before:hover:hover"),
             Ok(SelectorList::from_vec(vec![Selector::from_vec(
                 vec![
+                    Component::Combinator(Combinator::PseudoElement),
                     Component::PseudoElement(PseudoElement::Before),
                     Component::NonTSPseudoClass(PseudoClass::Hover),
                     Component::NonTSPseudoClass(PseudoClass::Hover),
@@ -2958,6 +2959,7 @@ pub mod tests {
                 specificity(0, 0, 0),
             )]))
         );
+
         assert_eq!(
             parse_ns(":not(svg|*)", &parser),
             Ok(SelectorList::from_vec(vec![Selector::from_vec(
@@ -3032,6 +3034,8 @@ pub mod tests {
             Some(&Component::PseudoElement(PseudoElement::Before))
         );
         assert_eq!(iter.next(), None);
+        assert_eq!(iter.next_sequence(), Some(Combinator::PseudoElement));
+        assert_eq!(iter.next(), None);
         assert_eq!(iter.next_sequence(), None);
     }
 
diff --git a/components/selectors/tree.rs b/components/selectors/tree.rs
index 52599893d2f..611e40d6027 100644
--- a/components/selectors/tree.rs
+++ b/components/selectors/tree.rs
@@ -47,9 +47,13 @@ pub trait Element: Sized + Clone + Debug {
     ///
     /// This is guaranteed to be called in a pseudo-element.
     fn pseudo_element_originating_element(&self) -> Option<Self> {
+        debug_assert!(self.is_pseudo_element());
         self.parent_element()
     }
 
+    /// Whether we're matching on a pseudo-element.
+    fn is_pseudo_element(&self) -> bool;
+
     /// Skips non-element nodes
     fn prev_sibling_element(&self) -> Option<Self>;
 
diff --git a/components/servo_arc/lib.rs b/components/servo_arc/lib.rs
index f2f9fa00602..09f381c62df 100644
--- a/components/servo_arc/lib.rs
+++ b/components/servo_arc/lib.rs
@@ -612,16 +612,15 @@ impl<H, T> Arc<HeaderSlice<H, [T]>> {
         use std::mem::{align_of, size_of};
         assert_ne!(size_of::<T>(), 0, "Need to think about ZST");
 
+        let inner_align = align_of::<ArcInner<HeaderSlice<H, [T; 0]>>>();
+        debug_assert!(inner_align >= align_of::<T>());
+
         // Compute the required size for the allocation.
         let num_items = items.len();
         let size = {
-            // First, determine the alignment of a hypothetical pointer to a
-            // HeaderSlice.
-            let fake_slice_ptr_align: usize = mem::align_of::<ArcInner<HeaderSlice<H, [T; 0]>>>();
-
             // Next, synthesize a totally garbage (but properly aligned) pointer
             // to a sequence of T.
-            let fake_slice_ptr = fake_slice_ptr_align as *const T;
+            let fake_slice_ptr = inner_align as *const T;
 
             // Convert that sequence to a fat pointer. The address component of
             // the fat pointer will be garbage, but the length will be correct.
@@ -641,13 +640,13 @@ impl<H, T> Arc<HeaderSlice<H, [T]>> {
         let ptr: *mut ArcInner<HeaderSlice<H, [T]>>;
         unsafe {
             // Allocate the buffer.
-            let layout = if mem::align_of::<T>() <= mem::align_of::<usize>() {
-                Layout::from_size_align_unchecked(size, mem::align_of::<usize>())
-            } else if mem::align_of::<T>() <= mem::align_of::<u64>() {
-                // On 32-bit platforms <T> may have 8 byte alignment while usize has 4 byte aligment.
-                // Use u64 to avoid over-alignment.
+            let layout = if inner_align <= align_of::<usize>() {
+                Layout::from_size_align_unchecked(size, align_of::<usize>())
+            } else if inner_align <= align_of::<u64>() {
+                // On 32-bit platforms <T> may have 8 byte alignment while usize
+                // has 4 byte aligment.  Use u64 to avoid over-alignment.
                 // This branch will compile away in optimized builds.
-                Layout::from_size_align_unchecked(size, mem::align_of::<u64>())
+                Layout::from_size_align_unchecked(size, align_of::<u64>())
             } else {
                 panic!("Over-aligned type not handled");
             };
@@ -689,7 +688,7 @@ impl<H, T> Arc<HeaderSlice<H, [T]>> {
                 // for some padding from the alignment.
                 debug_assert!(
                     (buffer.offset(size as isize) as usize - current as *mut u8 as usize) <
-                        align_of::<Self>()
+                        inner_align
                 );
             }
             assert!(
diff --git a/components/style/Cargo.toml b/components/style/Cargo.toml
index bf953a13f8f..4d5f3e2e94d 100644
--- a/components/style/Cargo.toml
+++ b/components/style/Cargo.toml
@@ -22,6 +22,7 @@ servo = ["serde", "style_traits/servo", "servo_atoms", "servo_config", "html5eve
          "cssparser/serde", "encoding_rs", "malloc_size_of/servo", "arrayvec/use_union",
          "servo_url", "string_cache", "crossbeam-channel", "to_shmem/servo", "servo_arc/servo"]
 gecko_debug = []
+gecko_profiler = []
 
 [dependencies]
 app_units = "0.7"
@@ -79,7 +80,7 @@ void = "1.0.2"
 [build-dependencies]
 lazy_static = "1"
 log = "0.4"
-bindgen = { version = "0.49", optional = true, default-features = false }
+bindgen = {version = "0.49", optional = true, default-features = false}
 regex = {version = "1.1", optional = true}
 walkdir = "2.1.4"
 toml = {version = "0.4.5", optional = true, default-features = false}
diff --git a/components/style/counter_style/mod.rs b/components/style/counter_style/mod.rs
index 77de5f52d2b..289281011c3 100644
--- a/components/style/counter_style/mod.rs
+++ b/components/style/counter_style/mod.rs
@@ -19,7 +19,6 @@ use selectors::parser::SelectorParseErrorKind;
 use std::fmt::{self, Write};
 use std::mem;
 use std::num::Wrapping;
-use std::ops::Range;
 use style_traits::{Comma, CssWriter, OneOrMoreSeparated, ParseError};
 use style_traits::{StyleParseErrorKind, ToCss};
 
@@ -261,7 +260,7 @@ counter_style_descriptors! {
     "suffix" suffix / set_suffix [_]: Symbol,
 
     /// <https://drafts.csswg.org/css-counter-styles/#counter-style-range>
-    "range" range / set_range [_]: Ranges,
+    "range" range / set_range [_]: CounterRanges,
 
     /// <https://drafts.csswg.org/css-counter-styles/#counter-style-pad>
     "pad" pad / set_pad [_]: Pad,
@@ -371,7 +370,7 @@ impl Parse for System {
             "additive" => Ok(System::Additive),
             "fixed" => {
                 let first_symbol_value = input.try(|i| Integer::parse(context, i)).ok();
-                Ok(System::Fixed { first_symbol_value: first_symbol_value })
+                Ok(System::Fixed { first_symbol_value })
             }
             "extends" => {
                 let other = parse_counter_style_name(input)?;
@@ -409,11 +408,10 @@ impl ToCss for System {
 }
 
 /// <https://drafts.csswg.org/css-counter-styles/#typedef-symbol>
-#[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-#[derive(Clone, Debug, Eq, PartialEq, ToComputedValue, ToCss, ToShmem)]
+#[derive(Clone, Debug, Eq, MallocSizeOf, PartialEq, ToComputedValue, ToCss, ToShmem)]
 pub enum Symbol {
     /// <string>
-    String(String),
+    String(crate::OwnedStr),
     /// <custom-ident>
     Ident(CustomIdent),
     // Not implemented:
@@ -428,7 +426,7 @@ impl Parse for Symbol {
     ) -> Result<Self, ParseError<'i>> {
         let location = input.current_source_location();
         match *input.next()? {
-            Token::QuotedString(ref s) => Ok(Symbol::String(s.as_ref().to_owned())),
+            Token::QuotedString(ref s) => Ok(Symbol::String(s.as_ref().to_owned().into())),
             Token::Ident(ref s) => Ok(Symbol::Ident(CustomIdent::from_ident(location, s, &[])?)),
             ref t => Err(location.new_unexpected_token_error(t.clone())),
         }
@@ -463,12 +461,22 @@ impl Parse for Negative {
 }
 
 /// <https://drafts.csswg.org/css-counter-styles/#counter-style-range>
+#[derive(Clone, Debug, ToCss, ToShmem)]
+pub struct CounterRange {
+    /// The start of the range.
+    pub start: CounterBound,
+    /// The end of the range.
+    pub end: CounterBound,
+}
+
+/// <https://drafts.csswg.org/css-counter-styles/#counter-style-range>
 ///
-/// Empty Vec represents 'auto'
-#[derive(Clone, Debug, ToShmem)]
-pub struct Ranges(pub Vec<Range<CounterBound>>);
+/// Empty represents 'auto'
+#[derive(Clone, Debug, ToCss, ToShmem)]
+#[css(comma)]
+pub struct CounterRanges(#[css(iterable, if_empty = "auto")] pub crate::OwnedSlice<CounterRange>);
 
-/// A bound found in `Ranges`.
+/// A bound found in `CounterRanges`.
 #[derive(Clone, Copy, Debug, ToCss, ToShmem)]
 pub enum CounterBound {
     /// An integer bound.
@@ -477,7 +485,7 @@ pub enum CounterBound {
     Infinite,
 }
 
-impl Parse for Ranges {
+impl Parse for CounterRanges {
     fn parse<'i, 't>(
         context: &ParserContext,
         input: &mut Parser<'i, 't>,
@@ -486,25 +494,21 @@ impl Parse for Ranges {
             .try(|input| input.expect_ident_matching("auto"))
             .is_ok()
         {
-            Ok(Ranges(Vec::new()))
-        } else {
-            input
-                .parse_comma_separated(|input| {
-                    let opt_start = parse_bound(context, input)?;
-                    let opt_end = parse_bound(context, input)?;
-                    if let (CounterBound::Integer(start), CounterBound::Integer(end)) =
-                        (opt_start, opt_end)
-                    {
-                        if start > end {
-                            return Err(
-                                input.new_custom_error(StyleParseErrorKind::UnspecifiedError)
-                            );
-                        }
-                    }
-                    Ok(opt_start..opt_end)
-                })
-                .map(Ranges)
+            return Ok(CounterRanges(Default::default()));
         }
+
+        let ranges = input.parse_comma_separated(|input| {
+            let start = parse_bound(context, input)?;
+            let end = parse_bound(context, input)?;
+            if let (CounterBound::Integer(start), CounterBound::Integer(end)) = (start, end) {
+                if start > end {
+                    return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
+                }
+            }
+            Ok(CounterRange { start, end })
+        })?;
+
+        Ok(CounterRanges(ranges.into()))
     }
 }
 
@@ -519,34 +523,6 @@ fn parse_bound<'i, 't>(
     Ok(CounterBound::Infinite)
 }
 
-impl ToCss for Ranges {
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: Write,
-    {
-        let mut iter = self.0.iter();
-        if let Some(first) = iter.next() {
-            range_to_css(first, dest)?;
-            for item in iter {
-                dest.write_str(", ")?;
-                range_to_css(item, dest)?;
-            }
-            Ok(())
-        } else {
-            dest.write_str("auto")
-        }
-    }
-}
-
-fn range_to_css<W>(range: &Range<CounterBound>, dest: &mut CssWriter<W>) -> fmt::Result
-where
-    W: Write,
-{
-    range.start.to_css(dest)?;
-    dest.write_char(' ')?;
-    range.end.to_css(dest)
-}
-
 /// <https://drafts.csswg.org/css-counter-styles/#counter-style-pad>
 #[derive(Clone, Debug, ToCss, ToShmem)]
 pub struct Pad(pub Integer, pub Symbol);
@@ -572,14 +548,13 @@ impl Parse for Fallback {
         _context: &ParserContext,
         input: &mut Parser<'i, 't>,
     ) -> Result<Self, ParseError<'i>> {
-        parse_counter_style_name(input).map(Fallback)
+        Ok(Fallback(parse_counter_style_name(input)?))
     }
 }
 
 /// <https://drafts.csswg.org/css-counter-styles/#descdef-counter-style-symbols>
-#[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-#[derive(Clone, Debug, Eq, PartialEq, ToComputedValue, ToCss, ToShmem)]
-pub struct Symbols(#[css(iterable)] pub Vec<Symbol>);
+#[derive(Clone, Debug, Eq, MallocSizeOf, PartialEq, ToComputedValue, ToCss, ToShmem)]
+pub struct Symbols(#[css(iterable)] pub crate::OwnedSlice<Symbol>);
 
 impl Parse for Symbols {
     fn parse<'i, 't>(
@@ -587,23 +562,20 @@ impl Parse for Symbols {
         input: &mut Parser<'i, 't>,
     ) -> Result<Self, ParseError<'i>> {
         let mut symbols = Vec::new();
-        loop {
-            if let Ok(s) = input.try(|input| Symbol::parse(context, input)) {
-                symbols.push(s)
-            } else {
-                if symbols.is_empty() {
-                    return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
-                } else {
-                    return Ok(Symbols(symbols));
-                }
-            }
+        while let Ok(s) = input.try(|input| Symbol::parse(context, input)) {
+            symbols.push(s);
+        }
+        if symbols.is_empty() {
+            return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
         }
+        Ok(Symbols(symbols.into()))
     }
 }
 
 /// <https://drafts.csswg.org/css-counter-styles/#descdef-counter-style-additive-symbols>
 #[derive(Clone, Debug, ToCss, ToShmem)]
-pub struct AdditiveSymbols(pub Vec<AdditiveTuple>);
+#[css(comma)]
+pub struct AdditiveSymbols(#[css(iterable)] pub crate::OwnedSlice<AdditiveTuple>);
 
 impl Parse for AdditiveSymbols {
     fn parse<'i, 't>(
@@ -618,7 +590,7 @@ impl Parse for AdditiveSymbols {
         {
             return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
         }
-        Ok(AdditiveSymbols(tuples))
+        Ok(AdditiveSymbols(tuples.into()))
     }
 }
 
@@ -643,10 +615,7 @@ impl Parse for AdditiveTuple {
         let symbol = input.try(|input| Symbol::parse(context, input));
         let weight = Integer::parse_non_negative(context, input)?;
         let symbol = symbol.or_else(|_| Symbol::parse(context, input))?;
-        Ok(AdditiveTuple {
-            weight: weight,
-            symbol: symbol,
-        })
+        Ok(Self { weight, symbol })
     }
 }
 
diff --git a/components/style/dom.rs b/components/style/dom.rs
index 9a81e2ec774..5ee8443b91d 100644
--- a/components/style/dom.rs
+++ b/components/style/dom.rs
@@ -779,7 +779,7 @@ pub trait TElement:
     /// element-backed pseudo-element, in which case we return the originating
     /// element.
     fn rule_hash_target(&self) -> Self {
-        if self.implemented_pseudo_element().is_some() {
+        if self.is_pseudo_element() {
             self.pseudo_element_originating_element()
                 .expect("Trying to collect rules for a detached pseudo-element")
         } else {
@@ -801,24 +801,29 @@ pub trait TElement:
     {
         use rule_collector::containing_shadow_ignoring_svg_use;
 
-        let mut doc_rules_apply = self.matches_user_and_author_rules();
+        let target = self.rule_hash_target();
+        if !target.matches_user_and_author_rules() {
+            return false;
+        }
+
+        let mut doc_rules_apply = true;
 
         // Use the same rules to look for the containing host as we do for rule
         // collection.
-        if let Some(shadow) = containing_shadow_ignoring_svg_use(*self) {
+        if let Some(shadow) = containing_shadow_ignoring_svg_use(target) {
             doc_rules_apply = false;
             if let Some(data) = shadow.style_data() {
                 f(data, shadow.host());
             }
         }
 
-        if let Some(shadow) = self.shadow_root() {
+        if let Some(shadow) = target.shadow_root() {
             if let Some(data) = shadow.style_data() {
                 f(data, shadow.host());
             }
         }
 
-        let mut current = self.assigned_slot();
+        let mut current = target.assigned_slot();
         while let Some(slot) = current {
             // Slots can only have assigned nodes when in a shadow tree.
             let shadow = slot.containing_shadow().unwrap();
diff --git a/components/style/driver.rs b/components/style/driver.rs
index e9433f73a03..6b05bc85281 100644
--- a/components/style/driver.rs
+++ b/components/style/driver.rs
@@ -134,6 +134,7 @@ pub fn traverse_dom<E, D>(
                 let drain = discovered.drain(..);
                 pool.install(|| {
                     rayon::scope(|scope| {
+                        profiler_label!(Style);
                         parallel::traverse_nodes(
                             drain,
                             DispatchMode::TailCall,
diff --git a/components/style/gecko/arc_types.rs b/components/style/gecko/arc_types.rs
index 309f2395085..7aed10b6568 100644
--- a/components/style/gecko/arc_types.rs
+++ b/components/style/gecko/arc_types.rs
@@ -23,7 +23,6 @@ use crate::gecko_bindings::structs::RawServoMediaRule;
 use crate::gecko_bindings::structs::RawServoMozDocumentRule;
 use crate::gecko_bindings::structs::RawServoNamespaceRule;
 use crate::gecko_bindings::structs::RawServoPageRule;
-use crate::gecko_bindings::structs::RawServoQuotes;
 use crate::gecko_bindings::structs::RawServoStyleRule;
 use crate::gecko_bindings::structs::RawServoStyleSheetContents;
 use crate::gecko_bindings::structs::RawServoSupportsRule;
@@ -40,7 +39,6 @@ use crate::stylesheets::{NamespaceRule, PageRule};
 use crate::stylesheets::{StyleRule, StylesheetContents, SupportsRule};
 use servo_arc::{Arc, ArcBorrow};
 use std::{mem, ptr};
-use values::computed::QuotePair;
 
 macro_rules! impl_arc_ffi {
     ($servo_type:ty => $gecko_type:ty[$addref:ident, $release:ident]) => {
@@ -115,9 +113,6 @@ impl_arc_ffi!(Locked<CounterStyleRule> => RawServoCounterStyleRule
 impl_arc_ffi!(CssUrlData => RawServoCssUrlData
               [Servo_CssUrlData_AddRef, Servo_CssUrlData_Release]);
 
-impl_arc_ffi!(Box<[QuotePair]> => RawServoQuotes
-              [Servo_Quotes_AddRef, Servo_Quotes_Release]);
-
 // ComputedStyle is not an opaque type on any side of FFI.
 // This means that doing the HasArcFFI type trick is actually unsound,
 // since it gives us a way to construct an Arc<ComputedStyle> from
diff --git a/components/style/gecko/boxed_types.rs b/components/style/gecko/boxed_types.rs
index b61c7708b2a..47fc4fe57dc 100644
--- a/components/style/gecko/boxed_types.rs
+++ b/components/style/gecko/boxed_types.rs
@@ -5,6 +5,7 @@
 //! FFI implementations for types listed in ServoBoxedTypeList.h.
 
 use crate::gecko_bindings::sugar::ownership::{HasBoxFFI, HasFFI, HasSimpleFFI};
+use crate::properties::animated_properties::AnimationValueMap;
 use to_shmem::SharedMemoryBuilder;
 
 // TODO(heycam): The FFI impls for most of the types in ServoBoxedTypeList.h are spread across
@@ -12,6 +13,15 @@ use to_shmem::SharedMemoryBuilder;
 // them more succinctly, like we do in arc_types.rs.
 
 #[cfg(feature = "gecko")]
+unsafe impl HasFFI for AnimationValueMap {
+    type FFIType = crate::gecko_bindings::bindings::RawServoAnimationValueMap;
+}
+#[cfg(feature = "gecko")]
+unsafe impl HasSimpleFFI for AnimationValueMap {}
+#[cfg(feature = "gecko")]
+unsafe impl HasBoxFFI for AnimationValueMap {}
+
+#[cfg(feature = "gecko")]
 unsafe impl HasFFI for SharedMemoryBuilder {
     type FFIType = crate::gecko_bindings::bindings::RawServoSharedMemoryBuilder;
 }
diff --git a/components/style/gecko/conversions.rs b/components/style/gecko/conversions.rs
index 43082a7c04a..06e201bf2b5 100644
--- a/components/style/gecko/conversions.rs
+++ b/components/style/gecko/conversions.rs
@@ -383,7 +383,6 @@ impl nsStyleImage {
                 let atom = bindings::Gecko_GetImageElement(self);
                 Some(GenericImage::Element(Atom::from_raw(atom)))
             },
-            _ => panic!("Unexpected image type"),
         }
     }
 
@@ -535,10 +534,8 @@ pub mod basic_shape {
     use crate::gecko_bindings::structs::{
         StyleGeometryBox, StyleShapeSource, StyleShapeSourceType,
     };
-    use crate::gecko_bindings::sugar::refptr::RefPtr;
     use crate::values::computed::basic_shape::{BasicShape, ClippingShape, FloatAreaShape};
     use crate::values::computed::motion::OffsetPath;
-    use crate::values::computed::url::ComputedUrl;
     use crate::values::generics::basic_shape::{GeometryBox, Path, ShapeBox, ShapeSource};
     use crate::values::specified::SVGPathData;
 
@@ -564,7 +561,7 @@ pub mod basic_shape {
                     };
                     Some(ShapeSource::Shape(shape, reference_box))
                 },
-                StyleShapeSourceType::URL | StyleShapeSourceType::Image => None,
+                StyleShapeSourceType::Image => None,
                 StyleShapeSourceType::Path => {
                     let path = self.to_svg_path().expect("expect an SVGPathData");
                     let fill = unsafe { &*self.__bindgen_anon_1.mSVGPath.as_ref().mPtr }.mFillRule;
@@ -587,16 +584,15 @@ pub mod basic_shape {
 
     impl<'a> From<&'a StyleShapeSource> for ClippingShape {
         fn from(other: &'a StyleShapeSource) -> Self {
+            use crate::values::generics::image::Image as GenericImage;
             match other.mType {
-                StyleShapeSourceType::URL => unsafe {
+                StyleShapeSourceType::Image => unsafe {
                     let shape_image = &*other.__bindgen_anon_1.mShapeImage.as_ref().mPtr;
-                    let other_url =
-                        RefPtr::new(*shape_image.__bindgen_anon_1.mURLValue.as_ref() as *mut _);
-                    let url = ComputedUrl::from_url_value(other_url);
-                    ShapeSource::ImageOrUrl(url)
-                },
-                StyleShapeSourceType::Image => {
-                    unreachable!("ClippingShape doesn't support Image!");
+                    let image = shape_image.into_image().expect("Cannot convert to Image");
+                    match image {
+                        GenericImage::Url(url) => ShapeSource::ImageOrUrl(url.0),
+                        _ => panic!("ClippingShape doesn't support non-url images"),
+                    }
                 },
                 _ => other
                     .into_shape_source()
@@ -608,9 +604,6 @@ pub mod basic_shape {
     impl<'a> From<&'a StyleShapeSource> for FloatAreaShape {
         fn from(other: &'a StyleShapeSource) -> Self {
             match other.mType {
-                StyleShapeSourceType::URL => {
-                    unreachable!("FloatAreaShape doesn't support URL!");
-                },
                 StyleShapeSourceType::Image => unsafe {
                     let shape_image = &*other.__bindgen_anon_1.mShapeImage.as_ref().mPtr;
                     let image = shape_image.into_image().expect("Cannot convert to Image");
@@ -632,7 +625,6 @@ pub mod basic_shape {
                 StyleShapeSourceType::None => OffsetPath::none(),
                 StyleShapeSourceType::Shape |
                 StyleShapeSourceType::Box |
-                StyleShapeSourceType::URL |
                 StyleShapeSourceType::Image => unreachable!("Unsupported offset-path type"),
             }
         }
diff --git a/components/style/gecko/mod.rs b/components/style/gecko/mod.rs
index fb332dcce6e..3ff2cfcf140 100644
--- a/components/style/gecko/mod.rs
+++ b/components/style/gecko/mod.rs
@@ -13,9 +13,10 @@ pub mod conversions;
 pub mod data;
 pub mod media_features;
 pub mod media_queries;
+#[cfg(feature = "gecko_profiler")]
+pub mod profiler;
 pub mod pseudo_element;
 pub mod restyle_damage;
-pub mod rules;
 pub mod selector_parser;
 pub mod snapshot;
 pub mod snapshot_helpers;
diff --git a/components/style/gecko/profiler.rs b/components/style/gecko/profiler.rs
new file mode 100644
index 00000000000..1f25dde04e7
--- /dev/null
+++ b/components/style/gecko/profiler.rs
@@ -0,0 +1,75 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//! Gecko profiler support.
+//!
+//! Use the `profiler_label!` macro from macros.rs.
+
+use crate::gecko_bindings::structs;
+
+/// A label describing a category of work that style threads can perform.
+pub enum ProfilerLabel {
+    /// Style computation.
+    Style,
+    /// Style sheet parsing.
+    Parse,
+}
+
+/// RAII object that constructs and destroys a C++ AutoProfilerLabel object
+/// pointed to be the specified reference.
+#[cfg(feature = "gecko_profiler")]
+pub struct AutoProfilerLabel<'a>(&'a mut structs::AutoProfilerLabel);
+
+#[cfg(feature = "gecko_profiler")]
+impl<'a> AutoProfilerLabel<'a> {
+    /// Creates a new AutoProfilerLabel with the specified label type.
+    ///
+    /// unsafe since the caller must ensure that `label` is allocated on the
+    /// stack.
+    #[inline]
+    pub unsafe fn new(
+        label: &mut structs::AutoProfilerLabel,
+        label_type: ProfilerLabel,
+    ) -> AutoProfilerLabel {
+        let category_pair = match label_type {
+            ProfilerLabel::Style => structs::JS::ProfilingCategoryPair_LAYOUT_StyleComputation,
+            ProfilerLabel::Parse => structs::JS::ProfilingCategoryPair_LAYOUT_CSSParsing,
+        };
+        structs::Gecko_Construct_AutoProfilerLabel(label, category_pair);
+        AutoProfilerLabel(label)
+    }
+}
+
+#[cfg(feature = "gecko_profiler")]
+impl<'a> Drop for AutoProfilerLabel<'a> {
+    #[inline]
+    fn drop(&mut self) {
+        unsafe {
+            structs::Gecko_Destroy_AutoProfilerLabel(self.0);
+        }
+    }
+}
+
+/// Whether the Gecko profiler is currently active.
+///
+/// This implementation must be kept in sync with
+/// `mozilla::profiler::detail::RacyFeatures::IsActive`.
+#[cfg(feature = "gecko_profiler")]
+#[inline]
+pub fn profiler_is_active() -> bool {
+    use self::structs::profiler::detail;
+    use std::mem;
+    use std::sync::atomic::{AtomicU32, Ordering};
+
+    let active_and_features: &AtomicU32 =
+        unsafe { mem::transmute(&detail::RacyFeatures_sActiveAndFeatures) };
+    (active_and_features.load(Ordering::Relaxed) & detail::RacyFeatures_Active) != 0
+}
+
+/// Always false when the Gecko profiler is disabled.
+#[cfg(not(feature = "gecko_profiler"))]
+#[inline]
+pub fn profiler_is_active() -> bool {
+    false
+}
diff --git a/components/style/gecko/rules.rs b/components/style/gecko/rules.rs
deleted file mode 100644
index 050a95754df..00000000000
--- a/components/style/gecko/rules.rs
+++ /dev/null
@@ -1,135 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-//! Bindings for CSS Rule objects
-
-use crate::counter_style::{self, CounterBound};
-use crate::gecko_bindings::structs::{self, nsCSSValue};
-use crate::gecko_bindings::sugar::ns_css_value::ToNsCssValue;
-
-impl<'a> ToNsCssValue for &'a counter_style::System {
-    fn convert(self, nscssvalue: &mut nsCSSValue) {
-        use crate::counter_style::System::*;
-        match *self {
-            Cyclic => nscssvalue.set_enum(structs::NS_STYLE_COUNTER_SYSTEM_CYCLIC as i32),
-            Numeric => nscssvalue.set_enum(structs::NS_STYLE_COUNTER_SYSTEM_NUMERIC as i32),
-            Alphabetic => nscssvalue.set_enum(structs::NS_STYLE_COUNTER_SYSTEM_ALPHABETIC as i32),
-            Symbolic => nscssvalue.set_enum(structs::NS_STYLE_COUNTER_SYSTEM_SYMBOLIC as i32),
-            Additive => nscssvalue.set_enum(structs::NS_STYLE_COUNTER_SYSTEM_ADDITIVE as i32),
-            Fixed {
-                ref first_symbol_value,
-            } => {
-                let mut a = nsCSSValue::null();
-                let mut b = nsCSSValue::null();
-                a.set_enum(structs::NS_STYLE_COUNTER_SYSTEM_FIXED as i32);
-                b.set_integer(first_symbol_value.map_or(1, |v| v.value()));
-                nscssvalue.set_pair(&a, &b);
-            },
-            Extends(ref other) => {
-                let mut a = nsCSSValue::null();
-                let mut b = nsCSSValue::null();
-                a.set_enum(structs::NS_STYLE_COUNTER_SYSTEM_EXTENDS as i32);
-                b.set_atom_ident(other.0.clone());
-                nscssvalue.set_pair(&a, &b);
-            },
-        }
-    }
-}
-
-impl<'a> ToNsCssValue for &'a counter_style::Negative {
-    fn convert(self, nscssvalue: &mut nsCSSValue) {
-        if let Some(ref second) = self.1 {
-            let mut a = nsCSSValue::null();
-            let mut b = nsCSSValue::null();
-            a.set_from(&self.0);
-            b.set_from(second);
-            nscssvalue.set_pair(&a, &b);
-        } else {
-            nscssvalue.set_from(&self.0)
-        }
-    }
-}
-
-impl<'a> ToNsCssValue for &'a counter_style::Symbol {
-    fn convert(self, nscssvalue: &mut nsCSSValue) {
-        match *self {
-            counter_style::Symbol::String(ref s) => nscssvalue.set_string(s),
-            counter_style::Symbol::Ident(ref s) => nscssvalue.set_ident_from_atom(&s.0),
-        }
-    }
-}
-
-impl<'a> ToNsCssValue for &'a counter_style::Ranges {
-    fn convert(self, nscssvalue: &mut nsCSSValue) {
-        if self.0.is_empty() {
-            nscssvalue.set_auto();
-        } else {
-            nscssvalue.set_pair_list(self.0.iter().map(|range| {
-                fn set_bound(bound: CounterBound, nscssvalue: &mut nsCSSValue) {
-                    if let CounterBound::Integer(finite) = bound {
-                        nscssvalue.set_integer(finite.value())
-                    } else {
-                        nscssvalue.set_enum(structs::NS_STYLE_COUNTER_RANGE_INFINITE as i32)
-                    }
-                }
-                let mut start = nsCSSValue::null();
-                let mut end = nsCSSValue::null();
-                set_bound(range.start, &mut start);
-                set_bound(range.end, &mut end);
-                (start, end)
-            }));
-        }
-    }
-}
-
-impl<'a> ToNsCssValue for &'a counter_style::Pad {
-    fn convert(self, nscssvalue: &mut nsCSSValue) {
-        let mut min_length = nsCSSValue::null();
-        let mut pad_with = nsCSSValue::null();
-        min_length.set_integer(self.0.value());
-        pad_with.set_from(&self.1);
-        nscssvalue.set_pair(&min_length, &pad_with);
-    }
-}
-
-impl<'a> ToNsCssValue for &'a counter_style::Fallback {
-    fn convert(self, nscssvalue: &mut nsCSSValue) {
-        nscssvalue.set_atom_ident(self.0 .0.clone())
-    }
-}
-
-impl<'a> ToNsCssValue for &'a counter_style::Symbols {
-    fn convert(self, nscssvalue: &mut nsCSSValue) {
-        nscssvalue.set_list(self.0.iter().map(|item| {
-            let mut value = nsCSSValue::null();
-            value.set_from(item);
-            value
-        }));
-    }
-}
-
-impl<'a> ToNsCssValue for &'a counter_style::AdditiveSymbols {
-    fn convert(self, nscssvalue: &mut nsCSSValue) {
-        nscssvalue.set_pair_list(self.0.iter().map(|tuple| {
-            let mut weight = nsCSSValue::null();
-            let mut symbol = nsCSSValue::null();
-            weight.set_integer(tuple.weight.value());
-            symbol.set_from(&tuple.symbol);
-            (weight, symbol)
-        }));
-    }
-}
-
-impl<'a> ToNsCssValue for &'a counter_style::SpeakAs {
-    fn convert(self, nscssvalue: &mut nsCSSValue) {
-        use crate::counter_style::SpeakAs::*;
-        match *self {
-            Auto => nscssvalue.set_auto(),
-            Bullets => nscssvalue.set_enum(structs::NS_STYLE_COUNTER_SPEAKAS_BULLETS as i32),
-            Numbers => nscssvalue.set_enum(structs::NS_STYLE_COUNTER_SPEAKAS_NUMBERS as i32),
-            Words => nscssvalue.set_enum(structs::NS_STYLE_COUNTER_SPEAKAS_WORDS as i32),
-            Other(ref other) => nscssvalue.set_atom_ident(other.0.clone()),
-        }
-    }
-}
diff --git a/components/style/gecko/url.rs b/components/style/gecko/url.rs
index 2da16043779..dbbb3399da7 100644
--- a/components/style/gecko/url.rs
+++ b/components/style/gecko/url.rs
@@ -310,13 +310,13 @@ impl ToComputedValue for SpecifiedImageUrl {
     type ComputedValue = ComputedImageUrl;
 
     #[inline]
-    fn to_computed_value(&self, _: &Context) -> Self::ComputedValue {
-        ComputedImageUrl(self.clone())
+    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
+        ComputedImageUrl(self.0.to_computed_value(context))
     }
 
     #[inline]
     fn from_computed_value(computed: &Self::ComputedValue) -> Self {
-        computed.0.clone()
+        SpecifiedImageUrl(ToComputedValue::from_computed_value(&computed.0))
     }
 }
 
@@ -378,7 +378,7 @@ impl ComputedUrl {
 
 /// The computed value of a CSS image `url()`.
 #[derive(Clone, Debug, Eq, MallocSizeOf, PartialEq)]
-pub struct ComputedImageUrl(pub SpecifiedImageUrl);
+pub struct ComputedImageUrl(pub ComputedUrl);
 
 impl ToCss for ComputedImageUrl {
     fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
@@ -395,22 +395,17 @@ impl ComputedImageUrl {
     /// Convert from nsStyleImageReques to ComputedImageUrl.
     pub unsafe fn from_image_request(image_request: &nsStyleImageRequest) -> Self {
         let url_value = image_request.mImageValue.to_safe();
-        let css_url = &*url_value.mCssUrl.mRawPtr;
-        let url = CssUrl(CssUrlData::as_arc(&css_url).clone_arc());
-        ComputedImageUrl(SpecifiedImageUrl(SpecifiedUrl {
-            url,
-            url_value: Box::new(URLValueSource::URLValue(url_value)),
-        }))
+        ComputedImageUrl(ComputedUrl::from_url_value(url_value))
     }
 
     /// Clone a new, strong reference to the Gecko URLValue.
     pub fn clone_url_value(&self) -> RefPtr<URLValue> {
-        (self.0).0.clone_url_value()
+        self.0.clone_url_value()
     }
 
     /// Get a raw pointer to the URLValue held by this ComputedImageUrl, for FFI.
     pub fn url_value_ptr(&self) -> *mut URLValue {
-        (self.0).0.url_value_ptr()
+        self.0.url_value_ptr()
     }
 }
 
diff --git a/components/style/gecko/values.rs b/components/style/gecko/values.rs
index 98fe90fe3d0..8df85339265 100644
--- a/components/style/gecko/values.rs
+++ b/components/style/gecko/values.rs
@@ -12,7 +12,6 @@ use crate::gecko_bindings::structs::{nsStyleCoord, CounterStylePtr};
 use crate::gecko_bindings::sugar::ns_style_coord::{CoordData, CoordDataMut, CoordDataValue};
 use crate::values::computed::{Angle, Length, LengthPercentage};
 use crate::values::computed::{Number, NumberOrPercentage, Percentage};
-use crate::values::generics::gecko::ScrollSnapPoint;
 use crate::values::generics::grid::{TrackBreadth, TrackKeyword};
 use crate::values::generics::length::LengthPercentageOrAuto;
 use crate::values::generics::{CounterStyleOrNone, NonNegative};
@@ -217,27 +216,6 @@ impl GeckoStyleCoordConvertible for Angle {
     }
 }
 
-impl GeckoStyleCoordConvertible for ScrollSnapPoint<LengthPercentage> {
-    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
-        match self.repeated() {
-            None => coord.set_value(CoordDataValue::None),
-            Some(l) => l.to_gecko_style_coord(coord),
-        };
-    }
-
-    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
-        use crate::gecko_bindings::structs::root::nsStyleUnit;
-
-        Some(match coord.unit() {
-            nsStyleUnit::eStyleUnit_None => ScrollSnapPoint::None,
-            _ => ScrollSnapPoint::Repeat(
-                LengthPercentage::from_gecko_style_coord(coord)
-                    .expect("coord could not convert to LengthPercentage"),
-            ),
-        })
-    }
-}
-
 /// Convert a given RGBA value to `nscolor`.
 pub fn convert_rgba_to_nscolor(rgba: &RGBA) -> u32 {
     ((rgba.alpha as u32) << 24) |
@@ -288,7 +266,7 @@ impl CounterStyleOrNone {
                     .0
                     .iter()
                     .map(|symbol| match *symbol {
-                        Symbol::String(ref s) => nsCStr::from(s),
+                        Symbol::String(ref s) => nsCStr::from(&**s),
                         Symbol::Ident(_) => unreachable!("Should not have identifier in symbols()"),
                     })
                     .collect();
@@ -333,7 +311,7 @@ impl CounterStyleOrNone {
                 let symbol_type = SymbolsType::from_gecko_keyword(anonymous.mSystem as u32);
                 let symbols = symbols
                     .iter()
-                    .map(|gecko_symbol| Symbol::String(gecko_symbol.to_string()))
+                    .map(|gecko_symbol| Symbol::String(gecko_symbol.to_string().into()))
                     .collect();
                 Either::First(CounterStyleOrNone::Symbols(symbol_type, Symbols(symbols)))
             }
diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index 9d987c56308..a1443d1ad8d 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -1098,7 +1098,7 @@ impl<'le> TElement for GeckoElement<'le> {
     type TraversalChildrenIterator = GeckoChildrenIterator<'le>;
 
     fn inheritance_parent(&self) -> Option<Self> {
-        if self.implemented_pseudo_element().is_some() {
+        if self.is_pseudo_element() {
             return self.pseudo_element_originating_element();
         }
 
@@ -1405,7 +1405,7 @@ impl<'le> TElement for GeckoElement<'le> {
 
     #[inline]
     fn matches_user_and_author_rules(&self) -> bool {
-        !self.rule_hash_target().is_in_native_anonymous_subtree()
+        !self.is_in_native_anonymous_subtree()
     }
 
     #[inline]
@@ -1471,7 +1471,7 @@ impl<'le> TElement for GeckoElement<'le> {
     #[inline]
     fn skip_item_display_fixup(&self) -> bool {
         debug_assert!(
-            self.implemented_pseudo_element().is_none(),
+            !self.is_pseudo_element(),
             "Just don't call me if I'm a pseudo, you should know the answer already"
         );
         self.is_root_of_native_anonymous_subtree()
@@ -1919,8 +1919,13 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
     }
 
     #[inline]
+    fn is_pseudo_element(&self) -> bool {
+        self.implemented_pseudo_element().is_some()
+    }
+
+    #[inline]
     fn pseudo_element_originating_element(&self) -> Option<Self> {
-        debug_assert!(self.implemented_pseudo_element().is_some());
+        debug_assert!(self.is_pseudo_element());
         let parent = self.closest_anon_subtree_root_parent()?;
 
         // FIXME(emilio): Special-case for <input type="number">s
diff --git a/components/style/gecko_bindings/sugar/mod.rs b/components/style/gecko_bindings/sugar/mod.rs
index de981bd289a..338236c175a 100644
--- a/components/style/gecko_bindings/sugar/mod.rs
+++ b/components/style/gecko_bindings/sugar/mod.rs
@@ -6,9 +6,6 @@
 
 mod ns_com_ptr;
 mod ns_compatibility;
-mod ns_css_shadow_array;
-mod ns_css_shadow_item;
-pub mod ns_css_value;
 mod ns_style_auto_array;
 pub mod ns_style_coord;
 mod ns_t_array;
diff --git a/components/style/gecko_bindings/sugar/ns_css_shadow_array.rs b/components/style/gecko_bindings/sugar/ns_css_shadow_array.rs
deleted file mode 100644
index c0c6c2d9e36..00000000000
--- a/components/style/gecko_bindings/sugar/ns_css_shadow_array.rs
+++ /dev/null
@@ -1,78 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-//! Rust helpers for Gecko's `nsCSSShadowArray`.
-
-use crate::gecko_bindings::bindings::Gecko_AddRefCSSShadowArrayArbitraryThread;
-use crate::gecko_bindings::bindings::Gecko_NewCSSShadowArray;
-use crate::gecko_bindings::bindings::Gecko_ReleaseCSSShadowArrayArbitraryThread;
-use crate::gecko_bindings::structs::{nsCSSShadowArray, nsCSSShadowItem, RefPtr};
-use std::ops::{Deref, DerefMut};
-use std::{ptr, slice};
-
-impl RefPtr<nsCSSShadowArray> {
-    /// Replaces the current `nsCSSShadowArray` with a new one of len `len`.
-    pub fn replace_with_new(&mut self, len: u32) {
-        unsafe {
-            if !self.mRawPtr.is_null() {
-                Gecko_ReleaseCSSShadowArrayArbitraryThread(self.mRawPtr);
-            }
-
-            self.mRawPtr = if len == 0 {
-                ptr::null_mut()
-            } else {
-                Gecko_NewCSSShadowArray(len)
-            }
-        }
-    }
-
-    /// Sets the value to other `nsCSSShadowArray`, bumping and decreasing
-    /// refcounts as needed.
-    ///
-    /// TODO(emilio): Seems like this could move to `refptr.rs`, and be more
-    /// generic.
-    pub fn copy_from(&mut self, other: &Self) {
-        unsafe {
-            if !self.mRawPtr.is_null() {
-                Gecko_ReleaseCSSShadowArrayArbitraryThread(self.mRawPtr);
-            }
-            if !other.mRawPtr.is_null() {
-                Gecko_AddRefCSSShadowArrayArbitraryThread(other.mRawPtr);
-            }
-
-            self.mRawPtr = other.mRawPtr;
-        }
-    }
-}
-
-impl Deref for RefPtr<nsCSSShadowArray> {
-    type Target = [nsCSSShadowItem];
-    fn deref(&self) -> &[nsCSSShadowItem] {
-        if self.mRawPtr.is_null() {
-            &[]
-        } else {
-            unsafe {
-                slice::from_raw_parts(
-                    (*self.mRawPtr).mArray.as_ptr(),
-                    (*self.mRawPtr).mLength as usize,
-                )
-            }
-        }
-    }
-}
-
-impl DerefMut for RefPtr<nsCSSShadowArray> {
-    fn deref_mut(&mut self) -> &mut [nsCSSShadowItem] {
-        if self.mRawPtr.is_null() {
-            &mut []
-        } else {
-            unsafe {
-                slice::from_raw_parts_mut(
-                    (*self.mRawPtr).mArray.as_mut_ptr(),
-                    (*self.mRawPtr).mLength as usize,
-                )
-            }
-        }
-    }
-}
diff --git a/components/style/gecko_bindings/sugar/ns_css_shadow_item.rs b/components/style/gecko_bindings/sugar/ns_css_shadow_item.rs
deleted file mode 100644
index 03d68576dea..00000000000
--- a/components/style/gecko_bindings/sugar/ns_css_shadow_item.rs
+++ /dev/null
@@ -1,59 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-//! Rust helpers for Gecko's `nsCSSShadowItem`.
-
-use crate::gecko_bindings::structs::nsCSSShadowItem;
-use crate::values::computed::effects::{BoxShadow, SimpleShadow};
-use app_units::Au;
-
-impl nsCSSShadowItem {
-    /// Sets this item from the given box shadow.
-    #[inline]
-    pub fn set_from_box_shadow(&mut self, shadow: BoxShadow) {
-        self.set_from_simple_shadow(shadow.base);
-        self.mSpread = shadow.spread.to_i32_au();
-        self.mInset = shadow.inset;
-    }
-
-    /// Returns this item as a box shadow.
-    #[inline]
-    pub fn to_box_shadow(&self) -> BoxShadow {
-        BoxShadow {
-            base: self.extract_simple_shadow(),
-            spread: Au(self.mSpread).into(),
-            inset: self.mInset,
-        }
-    }
-
-    /// Sets this item from the given simple shadow.
-    #[inline]
-    pub fn set_from_simple_shadow(&mut self, shadow: SimpleShadow) {
-        self.mXOffset = shadow.horizontal.to_i32_au();
-        self.mYOffset = shadow.vertical.to_i32_au();
-        self.mRadius = shadow.blur.0.to_i32_au();
-        self.mSpread = 0;
-        self.mInset = false;
-        self.mColor = shadow.color.into();
-    }
-
-    /// Gets a simple shadow from this item.
-    #[inline]
-    fn extract_simple_shadow(&self) -> SimpleShadow {
-        SimpleShadow {
-            color: self.mColor.into(),
-            horizontal: Au(self.mXOffset).into(),
-            vertical: Au(self.mYOffset).into(),
-            blur: Au(self.mRadius).into(),
-        }
-    }
-
-    /// Returns this item as a simple shadow.
-    #[inline]
-    pub fn to_simple_shadow(&self) -> SimpleShadow {
-        debug_assert_eq!(self.mSpread, 0);
-        debug_assert_eq!(self.mInset, false);
-        self.extract_simple_shadow()
-    }
-}
diff --git a/components/style/gecko_bindings/sugar/ns_css_value.rs b/components/style/gecko_bindings/sugar/ns_css_value.rs
deleted file mode 100644
index b59732bcc8e..00000000000
--- a/components/style/gecko_bindings/sugar/ns_css_value.rs
+++ /dev/null
@@ -1,424 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-//! Little helpers for `nsCSSValue`.
-
-use crate::gecko_bindings::bindings;
-use crate::gecko_bindings::structs;
-use crate::gecko_bindings::structs::{nsCSSUnit, nsCSSValue};
-use crate::gecko_bindings::structs::{nsCSSValueList, nsCSSValue_Array};
-use crate::gecko_string_cache::Atom;
-use crate::values::computed::{Angle, Length, LengthPercentage, Percentage};
-use crate::Zero;
-use std::marker::PhantomData;
-use std::mem;
-use std::ops::{Index, IndexMut};
-use std::slice;
-
-impl nsCSSValue {
-    /// Create a CSSValue with null unit, useful to be used as a return value.
-    #[inline]
-    pub fn null() -> Self {
-        unsafe { mem::zeroed() }
-    }
-
-    /// Returns true if this nsCSSValue is none.
-    #[inline]
-    pub fn is_none(&self) -> bool {
-        self.mUnit == nsCSSUnit::eCSSUnit_None
-    }
-
-    /// Returns this nsCSSValue value as an integer, unchecked in release
-    /// builds.
-    pub fn integer_unchecked(&self) -> i32 {
-        debug_assert!(
-            self.mUnit == nsCSSUnit::eCSSUnit_Integer ||
-                self.mUnit == nsCSSUnit::eCSSUnit_Enumerated
-        );
-        unsafe { *self.mValue.mInt.as_ref() }
-    }
-
-    /// Checks if it is an integer and returns it if so
-    pub fn integer(&self) -> Option<i32> {
-        if self.mUnit == nsCSSUnit::eCSSUnit_Integer || self.mUnit == nsCSSUnit::eCSSUnit_Enumerated
-        {
-            Some(unsafe { *self.mValue.mInt.as_ref() })
-        } else {
-            None
-        }
-    }
-
-    /// Returns this nsCSSValue value as a floating point value, unchecked in
-    /// release builds.
-    pub fn float_unchecked(&self) -> f32 {
-        debug_assert!(nsCSSUnit::eCSSUnit_Number as u32 <= self.mUnit as u32);
-        unsafe { *self.mValue.mFloat.as_ref() }
-    }
-
-    /// Returns this nsCSSValue as a nsCSSValue::Array, unchecked in release
-    /// builds.
-    pub unsafe fn array_unchecked(&self) -> &nsCSSValue_Array {
-        debug_assert!(
-            nsCSSUnit::eCSSUnit_Array as u32 <= self.mUnit as u32 &&
-                self.mUnit as u32 <= nsCSSUnit::eCSSUnit_Calc_Plus as u32
-        );
-        let array = *self.mValue.mArray.as_ref();
-        debug_assert!(!array.is_null());
-        &*array
-    }
-
-    /// Sets LengthPercentage value to this nsCSSValue.
-    pub unsafe fn set_length_percentage(&mut self, lp: LengthPercentage) {
-        if lp.was_calc {
-            return bindings::Gecko_CSSValue_SetCalc(self, lp.into());
-        }
-        debug_assert!(!lp.has_percentage || lp.unclamped_length() == Length::zero());
-        if lp.has_percentage {
-            return self.set_percentage(lp.percentage());
-        }
-        self.set_px(lp.unclamped_length().px());
-    }
-
-    /// Sets a px value to this nsCSSValue.
-    pub unsafe fn set_px(&mut self, px: f32) {
-        bindings::Gecko_CSSValue_SetPixelLength(self, px)
-    }
-
-    /// Sets a percentage value to this nsCSSValue.
-    pub unsafe fn set_percentage(&mut self, unit_value: f32) {
-        bindings::Gecko_CSSValue_SetPercentage(self, unit_value)
-    }
-
-    /// Returns LengthPercentage value.
-    pub unsafe fn get_length_percentage(&self) -> LengthPercentage {
-        match self.mUnit {
-            nsCSSUnit::eCSSUnit_Pixel => {
-                LengthPercentage::new(Length::new(bindings::Gecko_CSSValue_GetNumber(self)), None)
-            },
-            nsCSSUnit::eCSSUnit_Percent => LengthPercentage::new_percent(Percentage(
-                bindings::Gecko_CSSValue_GetPercentage(self),
-            )),
-            nsCSSUnit::eCSSUnit_Calc => bindings::Gecko_CSSValue_GetCalc(self).into(),
-            _ => panic!("Unexpected unit"),
-        }
-    }
-
-    /// Returns Length  value.
-    pub unsafe fn get_length(&self) -> Length {
-        match self.mUnit {
-            nsCSSUnit::eCSSUnit_Pixel => Length::new(bindings::Gecko_CSSValue_GetNumber(self)),
-            _ => panic!("Unexpected unit"),
-        }
-    }
-
-    fn set_valueless_unit(&mut self, unit: nsCSSUnit) {
-        debug_assert_eq!(self.mUnit, nsCSSUnit::eCSSUnit_Null);
-        debug_assert!(
-            unit as u32 <= nsCSSUnit::eCSSUnit_DummyInherit as u32,
-            "Not a valueless unit"
-        );
-        self.mUnit = unit;
-    }
-
-    /// Set to an auto value
-    ///
-    /// This method requires the current value to be null.
-    pub fn set_auto(&mut self) {
-        self.set_valueless_unit(nsCSSUnit::eCSSUnit_Auto);
-    }
-
-    /// Set to a normal value
-    ///
-    /// This method requires the current value to be null.
-    pub fn set_normal(&mut self) {
-        self.set_valueless_unit(nsCSSUnit::eCSSUnit_Normal);
-    }
-
-    fn set_string_internal(&mut self, s: &str, unit: nsCSSUnit) {
-        unsafe { bindings::Gecko_CSSValue_SetString(self, s.as_ptr(), s.len() as u32, unit) }
-    }
-
-    fn set_string_from_atom_internal(&mut self, s: &Atom, unit: nsCSSUnit) {
-        unsafe { bindings::Gecko_CSSValue_SetStringFromAtom(self, s.as_ptr(), unit) }
-    }
-
-    /// Set to a string value
-    pub fn set_string(&mut self, s: &str) {
-        self.set_string_internal(s, nsCSSUnit::eCSSUnit_String)
-    }
-
-    /// Set to a string value from the given atom
-    pub fn set_string_from_atom(&mut self, s: &Atom) {
-        self.set_string_from_atom_internal(s, nsCSSUnit::eCSSUnit_String)
-    }
-
-    /// Set to a ident value from the given atom
-    pub fn set_ident_from_atom(&mut self, s: &Atom) {
-        self.set_string_from_atom_internal(s, nsCSSUnit::eCSSUnit_Ident)
-    }
-
-    /// Set to an identifier value
-    pub fn set_ident(&mut self, s: &str) {
-        self.set_string_internal(s, nsCSSUnit::eCSSUnit_Ident)
-    }
-
-    /// Set to an atom identifier value
-    pub fn set_atom_ident(&mut self, s: Atom) {
-        unsafe { bindings::Gecko_CSSValue_SetAtomIdent(self, s.into_addrefed()) }
-    }
-
-    fn set_int_internal(&mut self, value: i32, unit: nsCSSUnit) {
-        unsafe { bindings::Gecko_CSSValue_SetInt(self, value, unit) }
-    }
-
-    /// Set to an integer value
-    pub fn set_integer(&mut self, value: i32) {
-        self.set_int_internal(value, nsCSSUnit::eCSSUnit_Integer)
-    }
-
-    /// Set to an enumerated value
-    pub fn set_enum<T: Into<i32>>(&mut self, value: T) {
-        self.set_int_internal(value.into(), nsCSSUnit::eCSSUnit_Enumerated);
-    }
-
-    /// Set to a number value
-    pub fn set_number(&mut self, number: f32) {
-        unsafe { bindings::Gecko_CSSValue_SetFloat(self, number, nsCSSUnit::eCSSUnit_Number) }
-    }
-
-    /// Set to an array of given length
-    pub fn set_array(&mut self, len: i32) -> &mut nsCSSValue_Array {
-        unsafe { bindings::Gecko_CSSValue_SetArray(self, len) }
-        unsafe { self.mValue.mArray.as_mut().as_mut() }.unwrap()
-    }
-
-    /// Generic set from any value that implements the ToNsCssValue trait.
-    pub fn set_from<T: ToNsCssValue>(&mut self, value: T) {
-        value.convert(self)
-    }
-
-    /// Returns an `Angle` value from this `nsCSSValue`.
-    ///
-    /// Panics if the unit is not `eCSSUnit_Degree`.
-    #[inline]
-    pub fn get_angle(&self) -> Angle {
-        debug_assert_eq!(self.mUnit, nsCSSUnit::eCSSUnit_Degree);
-        Angle::from_degrees(self.float_unchecked())
-    }
-
-    /// Sets Angle value to this nsCSSValue.
-    pub fn set_angle(&mut self, angle: Angle) {
-        debug_assert_eq!(self.mUnit, nsCSSUnit::eCSSUnit_Null);
-        self.mUnit = nsCSSUnit::eCSSUnit_Degree;
-        unsafe {
-            *self.mValue.mFloat.as_mut() = angle.degrees();
-        }
-    }
-
-    /// Set to a pair value
-    ///
-    /// This is only supported on the main thread.
-    pub fn set_pair(&mut self, x: &nsCSSValue, y: &nsCSSValue) {
-        unsafe { bindings::Gecko_CSSValue_SetPair(self, x, y) }
-    }
-
-    /// Set to a list value
-    ///
-    /// This is only supported on the main thread.
-    pub fn set_list<I>(&mut self, values: I)
-    where
-        I: ExactSizeIterator<Item = nsCSSValue>,
-    {
-        debug_assert!(values.len() > 0, "Empty list is not supported");
-        unsafe {
-            bindings::Gecko_CSSValue_SetList(self, values.len() as u32);
-        }
-        debug_assert_eq!(self.mUnit, nsCSSUnit::eCSSUnit_List);
-        let list: &mut structs::nsCSSValueList = &mut unsafe {
-            self.mValue
-                .mList
-                .as_ref() // &*nsCSSValueList_heap
-                .as_mut()
-                .expect("List pointer should be non-null")
-        }
-        ._base;
-        for (item, new_value) in list.into_iter().zip(values) {
-            *item = new_value;
-        }
-    }
-
-    /// Set to a pair list value
-    ///
-    /// This is only supported on the main thread.
-    pub fn set_pair_list<I>(&mut self, mut values: I)
-    where
-        I: ExactSizeIterator<Item = (nsCSSValue, nsCSSValue)>,
-    {
-        debug_assert!(values.len() > 0, "Empty list is not supported");
-        unsafe {
-            bindings::Gecko_CSSValue_SetPairList(self, values.len() as u32);
-        }
-        debug_assert_eq!(self.mUnit, nsCSSUnit::eCSSUnit_PairList);
-        let mut item_ptr = &mut unsafe {
-            self.mValue
-                .mPairList
-                .as_ref() // &*nsCSSValuePairList_heap
-                .as_mut()
-                .expect("List pointer should be non-null")
-        }
-        ._base as *mut structs::nsCSSValuePairList;
-        while let Some(item) = unsafe { item_ptr.as_mut() } {
-            let value = values.next().expect("Values shouldn't have been exhausted");
-            item.mXValue = value.0;
-            item.mYValue = value.1;
-            item_ptr = item.mNext;
-        }
-        debug_assert!(values.next().is_none(), "Values should have been exhausted");
-    }
-
-    /// Set a shared list
-    pub fn set_shared_list<I>(&mut self, values: I)
-    where
-        I: ExactSizeIterator<Item = nsCSSValue>,
-    {
-        debug_assert!(values.len() > 0, "Empty list is not supported");
-        unsafe { bindings::Gecko_CSSValue_InitSharedList(self, values.len() as u32) };
-        debug_assert_eq!(self.mUnit, nsCSSUnit::eCSSUnit_SharedList);
-        let list = unsafe {
-            self.mValue
-                .mSharedList
-                .as_ref()
-                .as_mut()
-                .expect("List pointer should be non-null")
-                .mHead
-                .as_mut()
-        };
-        debug_assert!(list.is_some(), "New created shared list shouldn't be null");
-        for (item, new_value) in list.unwrap().into_iter().zip(values) {
-            *item = new_value;
-        }
-    }
-}
-
-impl Drop for nsCSSValue {
-    fn drop(&mut self) {
-        unsafe { bindings::Gecko_CSSValue_Drop(self) };
-    }
-}
-
-/// Iterator of nsCSSValueList.
-#[allow(non_camel_case_types)]
-pub struct nsCSSValueListIterator<'a> {
-    current: Option<&'a nsCSSValueList>,
-}
-
-impl<'a> Iterator for nsCSSValueListIterator<'a> {
-    type Item = &'a nsCSSValue;
-    fn next(&mut self) -> Option<Self::Item> {
-        match self.current {
-            Some(item) => {
-                self.current = unsafe { item.mNext.as_ref() };
-                Some(&item.mValue)
-            },
-            None => None,
-        }
-    }
-}
-
-impl<'a> IntoIterator for &'a nsCSSValueList {
-    type Item = &'a nsCSSValue;
-    type IntoIter = nsCSSValueListIterator<'a>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        nsCSSValueListIterator {
-            current: Some(self),
-        }
-    }
-}
-
-/// Mutable Iterator of nsCSSValueList.
-#[allow(non_camel_case_types)]
-pub struct nsCSSValueListMutIterator<'a> {
-    current: *mut nsCSSValueList,
-    phantom: PhantomData<&'a mut nsCSSValue>,
-}
-
-impl<'a> Iterator for nsCSSValueListMutIterator<'a> {
-    type Item = &'a mut nsCSSValue;
-    fn next(&mut self) -> Option<Self::Item> {
-        match unsafe { self.current.as_mut() } {
-            Some(item) => {
-                self.current = item.mNext;
-                Some(&mut item.mValue)
-            },
-            None => None,
-        }
-    }
-}
-
-impl<'a> IntoIterator for &'a mut nsCSSValueList {
-    type Item = &'a mut nsCSSValue;
-    type IntoIter = nsCSSValueListMutIterator<'a>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        nsCSSValueListMutIterator {
-            current: self as *mut nsCSSValueList,
-            phantom: PhantomData,
-        }
-    }
-}
-
-impl nsCSSValue_Array {
-    /// Return the length of this `nsCSSValue::Array`
-    #[inline]
-    pub fn len(&self) -> usize {
-        self.mCount
-    }
-
-    #[inline]
-    fn buffer(&self) -> *const nsCSSValue {
-        self.mArray.as_ptr()
-    }
-
-    /// Get the array as a slice of nsCSSValues.
-    #[inline]
-    pub fn as_slice(&self) -> &[nsCSSValue] {
-        unsafe { slice::from_raw_parts(self.buffer(), self.len()) }
-    }
-
-    /// Get the array as a mutable slice of nsCSSValues.
-    #[inline]
-    pub fn as_mut_slice(&mut self) -> &mut [nsCSSValue] {
-        unsafe { slice::from_raw_parts_mut(self.buffer() as *mut _, self.len()) }
-    }
-}
-
-impl Index<usize> for nsCSSValue_Array {
-    type Output = nsCSSValue;
-    #[inline]
-    fn index(&self, i: usize) -> &nsCSSValue {
-        &self.as_slice()[i]
-    }
-}
-
-impl IndexMut<usize> for nsCSSValue_Array {
-    #[inline]
-    fn index_mut(&mut self, i: usize) -> &mut nsCSSValue {
-        &mut self.as_mut_slice()[i]
-    }
-}
-
-/// Generic conversion to nsCSSValue
-pub trait ToNsCssValue {
-    /// Convert
-    fn convert(self, nscssvalue: &mut nsCSSValue);
-}
-
-impl<T: ToNsCssValue> From<T> for nsCSSValue {
-    fn from(value: T) -> nsCSSValue {
-        let mut result = nsCSSValue::null();
-        value.convert(&mut result);
-        result
-    }
-}
diff --git a/components/style/gecko_bindings/sugar/refptr.rs b/components/style/gecko_bindings/sugar/refptr.rs
index 1ad71afa6bc..90cc5284bc4 100644
--- a/components/style/gecko_bindings/sugar/refptr.rs
+++ b/components/style/gecko_bindings/sugar/refptr.rs
@@ -290,11 +290,6 @@ impl_threadsafe_refcount!(
     bindings::Gecko_ReleaseURLExtraDataArbitraryThread
 );
 impl_threadsafe_refcount!(
-    structs::nsCSSValueSharedList,
-    bindings::Gecko_AddRefCSSValueSharedListArbitraryThread,
-    bindings::Gecko_ReleaseCSSValueSharedListArbitraryThread
-);
-impl_threadsafe_refcount!(
     structs::mozilla::css::URLValue,
     bindings::Gecko_AddRefCSSURLValueArbitraryThread,
     bindings::Gecko_ReleaseCSSURLValueArbitraryThread
diff --git a/components/style/gecko_string_cache/mod.rs b/components/style/gecko_string_cache/mod.rs
index d71d192166a..b8f3ff7f048 100644
--- a/components/style/gecko_string_cache/mod.rs
+++ b/components/style/gecko_string_cache/mod.rs
@@ -53,6 +53,7 @@ macro_rules! local_name {
 /// This is either a strong reference to a dynamic atom (an nsAtom pointer),
 /// or an offset from gGkAtoms to the nsStaticAtom object.
 #[derive(Eq, PartialEq)]
+#[repr(C)]
 pub struct Atom(usize);
 
 /// An atom *without* a strong reference.
diff --git a/components/style/invalidation/element/element_wrapper.rs b/components/style/invalidation/element/element_wrapper.rs
index 6e8e504c226..91f0705853c 100644
--- a/components/style/invalidation/element/element_wrapper.rs
+++ b/components/style/invalidation/element/element_wrapper.rs
@@ -366,6 +366,10 @@ where
         self.element.is_root()
     }
 
+    fn is_pseudo_element(&self) -> bool {
+        self.element.is_pseudo_element()
+    }
+
     fn pseudo_element_originating_element(&self) -> Option<Self> {
         self.element
             .pseudo_element_originating_element()
diff --git a/components/style/lib.rs b/components/style/lib.rs
index 4d523d65c4f..587b926efc6 100644
--- a/components/style/lib.rs
+++ b/components/style/lib.rs
@@ -190,6 +190,7 @@ pub use servo_atoms::Atom;
 
 pub use style_traits::arc_slice::ArcSlice;
 pub use style_traits::owned_slice::OwnedSlice;
+pub use style_traits::owned_str::OwnedStr;
 
 /// The CSS properties supported by the style system.
 /// Generated from the properties.mako.rs template by build.rs
diff --git a/components/style/macros.rs b/components/style/macros.rs
index 22f1966071b..229e864977a 100644
--- a/components/style/macros.rs
+++ b/components/style/macros.rs
@@ -104,3 +104,32 @@ macro_rules! define_keyword_type {
         }
     };
 }
+
+/// Place a Gecko profiler label on the stack.
+///
+/// The `label_type` argument must be the name of a variant of `ProfilerLabel`.
+#[cfg(feature = "gecko_profiler")]
+#[macro_export]
+macro_rules! profiler_label {
+    ($label_type:ident) => {
+        let mut _profiler_label: $crate::gecko_bindings::structs::AutoProfilerLabel =
+            unsafe { ::std::mem::uninitialized() };
+        let _profiler_label = if $crate::gecko::profiler::profiler_is_active() {
+            unsafe {
+                Some($crate::gecko::profiler::AutoProfilerLabel::new(
+                    &mut _profiler_label,
+                    $crate::gecko::profiler::ProfilerLabel::$label_type,
+                ))
+            }
+        } else {
+            None
+        };
+    };
+}
+
+/// No-op when the Gecko profiler is not available.
+#[cfg(not(feature = "gecko_profiler"))]
+#[macro_export]
+macro_rules! profiler_label {
+    ($label_type:ident) => {};
+}
diff --git a/components/style/parallel.rs b/components/style/parallel.rs
index 237453084df..619be351579 100644
--- a/components/style/parallel.rs
+++ b/components/style/parallel.rs
@@ -277,6 +277,7 @@ pub fn traverse_nodes<'a, 'scope, E, D, I>(
             top_down_dom(&work, root, traversal_data, scope, pool, traversal, tls);
         } else {
             scope.spawn(move |scope| {
+                profiler_label!(Style);
                 let work = work;
                 top_down_dom(&work, root, traversal_data, scope, pool, traversal, tls);
             });
@@ -286,6 +287,7 @@ pub fn traverse_nodes<'a, 'scope, E, D, I>(
             let nodes: WorkUnit<E::ConcreteNode> = chunk.collect();
             let traversal_data_copy = traversal_data.clone();
             scope.spawn(move |scope| {
+                profiler_label!(Style);
                 let n = nodes;
                 top_down_dom(&*n, root, traversal_data_copy, scope, pool, traversal, tls)
             });
diff --git a/components/style/properties/cascade.rs b/components/style/properties/cascade.rs
index 1b76aefdd74..9b1cfb8ec04 100644
--- a/components/style/properties/cascade.rs
+++ b/components/style/properties/cascade.rs
@@ -628,10 +628,6 @@ impl<'a, 'b: 'a> Cascade<'a, 'b> {
 
         #[cfg(feature = "gecko")]
         {
-            if let Some(display) = builder.get_box_if_mutated() {
-                display.generate_combined_transform();
-            }
-
             if let Some(bg) = builder.get_background_if_mutated() {
                 bg.fill_arrays();
             }
diff --git a/components/style/properties/data.py b/components/style/properties/data.py
index ae307077690..e771607b6d9 100644
--- a/components/style/properties/data.py
+++ b/components/style/properties/data.py
@@ -172,8 +172,9 @@ class Longhand(object):
                  gecko_ffi_name=None,
                  allowed_in_keyframe_block=True, cast_type='u8',
                  logical=False, logical_group=None, alias=None, extra_prefixes=None, boxed=False,
-                 flags=None, allowed_in_page_rule=False, allow_quirks=False,
+                 flags=None, allowed_in_page_rule=False, allow_quirks="No",
                  ignored_when_colors_disabled=False,
+                 simple_vector_bindings=False,
                  vector=False, servo_restyle_damage="repaint"):
         self.name = name
         if not spec:
@@ -210,6 +211,7 @@ class Longhand(object):
         self.allow_quirks = allow_quirks
         self.ignored_when_colors_disabled = ignored_when_colors_disabled
         self.is_vector = vector
+        self.simple_vector_bindings = simple_vector_bindings
 
         # https://drafts.csswg.org/css-animations/#keyframes
         # > The <declaration-list> inside of <keyframe-block> accepts any CSS property
@@ -323,12 +325,14 @@ class Longhand(object):
                 "JustifyContent",
                 "JustifyItems",
                 "JustifySelf",
+                "LineBreak",
                 "MozForceBrokenImageIcon",
                 "MozListReversed",
                 "MozScriptLevel",
                 "MozScriptMinSize",
                 "MozScriptSizeMultiplier",
                 "NonNegativeNumber",
+                "OffsetRotate",
                 "Opacity",
                 "OutlineStyle",
                 "Overflow",
diff --git a/components/style/properties/declaration_block.rs b/components/style/properties/declaration_block.rs
index 1ce083c944f..fcbfb717aa8 100644
--- a/components/style/properties/declaration_block.rs
+++ b/components/style/properties/declaration_block.rs
@@ -1301,11 +1301,9 @@ impl<'a, 'b, 'i> DeclarationParser<'i> for PropertyDeclarationParser<'a, 'b> {
             Ok(id) => id,
             Err(..) => {
                 self.last_parsed_property_id = None;
-                return Err(input.new_custom_error(if is_non_mozilla_vendor_identifier(&name) {
-                    StyleParseErrorKind::UnknownVendorProperty
-                } else {
+                return Err(input.new_custom_error(
                     StyleParseErrorKind::UnknownProperty(name)
-                }));
+                ));
             }
         };
         if self.context.error_reporting_enabled() {
@@ -1326,6 +1324,13 @@ impl<'a, 'b, 'i> DeclarationParser<'i> for PropertyDeclarationParser<'a, 'b> {
 
 type SmallParseErrorVec<'i> = SmallVec<[(ParseError<'i>, &'i str, Option<PropertyId>); 2]>;
 
+fn alias_of_known_property(name: &str) -> Option<PropertyId> {
+    let mut prefixed = String::with_capacity(name.len() + 5);
+    prefixed.push_str("-moz-");
+    prefixed.push_str(name);
+    PropertyId::parse_enabled_for_all_content(&prefixed).ok()
+}
+
 #[cold]
 fn report_one_css_error<'i>(
     context: &ParserContext,
@@ -1352,10 +1357,22 @@ fn report_one_css_error<'i>(
         }
     }
 
-    // If the unrecognized property looks like a vendor-specific property,
-    // silently ignore it instead of polluting the error output.
-    if let ParseErrorKind::Custom(StyleParseErrorKind::UnknownVendorProperty) = error.kind {
-        return;
+    if let ParseErrorKind::Custom(StyleParseErrorKind::UnknownProperty(ref name)) = error.kind {
+        if is_non_mozilla_vendor_identifier(name) {
+            // If the unrecognized property looks like a vendor-specific property,
+            // silently ignore it instead of polluting the error output.
+            return;
+        }
+        if let Some(alias) = alias_of_known_property(name) {
+            // This is an unknown property, but its -moz-* version is known.
+            // We don't want to report error if the -moz-* version is already
+            // specified.
+            if let Some(block) = block {
+                if all_properties_in_block(block, &alias) {
+                    return;
+                }
+            }
+        }
     }
 
     if let Some(ref property) = property {
diff --git a/components/style/properties/gecko.mako.rs b/components/style/properties/gecko.mako.rs
index 703cbed2c0b..dd5bcf2febf 100644
--- a/components/style/properties/gecko.mako.rs
+++ b/components/style/properties/gecko.mako.rs
@@ -28,7 +28,6 @@ use crate::gecko_bindings::bindings::Gecko_CopyListStyleImageFrom;
 use crate::gecko_bindings::bindings::Gecko_EnsureImageLayersLength;
 use crate::gecko_bindings::bindings::Gecko_SetCursorArrayLength;
 use crate::gecko_bindings::bindings::Gecko_SetCursorImageValue;
-use crate::gecko_bindings::bindings::Gecko_NewCSSShadowArray;
 use crate::gecko_bindings::bindings::Gecko_nsStyleFont_SetLang;
 use crate::gecko_bindings::bindings::Gecko_nsStyleFont_CopyLangFrom;
 use crate::gecko_bindings::bindings::Gecko_SetListStyleImageNone;
@@ -50,17 +49,19 @@ use crate::rule_tree::StrongRuleNode;
 use crate::selector_parser::PseudoElement;
 use servo_arc::{Arc, RawOffsetArc};
 use std::marker::PhantomData;
-use std::mem::{forget, uninitialized, zeroed};
+use std::mem::{forget, uninitialized, zeroed, ManuallyDrop};
 use std::{cmp, ops, ptr};
 use crate::values::{self, CustomIdent, Either, KeyframesName, None_};
 use crate::values::computed::{NonNegativeLength, Percentage, TransitionProperty};
+use crate::values::computed::url::ComputedImageUrl;
 use crate::values::computed::BorderStyle;
 use crate::values::computed::font::FontSize;
-use crate::values::computed::effects::{BoxShadow, Filter, SimpleShadow};
+use crate::values::computed::effects::Filter;
 use crate::values::generics::column::ColumnCount;
 use crate::values::generics::transform::TransformStyle;
 use crate::values::generics::url::UrlOrNone;
 
+
 pub mod style_structs {
     % for style_struct in data.style_structs:
     pub use super::${style_struct.gecko_struct_name} as ${style_struct.name};
@@ -303,14 +304,14 @@ impl ${style_struct.gecko_struct_name} {
 <%def name="impl_simple_clone(ident, gecko_ffi_name)">
     #[allow(non_snake_case)]
     pub fn clone_${ident}(&self) -> longhands::${ident}::computed_value::T {
-        From::from(self.gecko.${gecko_ffi_name})
+        From::from(self.gecko.${gecko_ffi_name}.clone())
     }
 </%def>
 
 <%def name="impl_simple_copy(ident, gecko_ffi_name, *kwargs)">
     #[allow(non_snake_case)]
     pub fn copy_${ident}_from(&mut self, other: &Self) {
-        self.gecko.${gecko_ffi_name} = other.gecko.${gecko_ffi_name};
+        self.gecko.${gecko_ffi_name} = other.gecko.${gecko_ffi_name}.clone();
     }
 
     #[allow(non_snake_case)]
@@ -697,45 +698,6 @@ def set_gecko_property(ffi_name, expr):
     }
 </%def>
 
-<%def name="impl_style_coord(ident, gecko_ffi_name)">
-    #[allow(non_snake_case)]
-    pub fn set_${ident}(&mut self, v: longhands::${ident}::computed_value::T) {
-        v.to_gecko_style_coord(&mut self.gecko.${gecko_ffi_name});
-    }
-    #[allow(non_snake_case)]
-    pub fn copy_${ident}_from(&mut self, other: &Self) {
-        self.gecko.${gecko_ffi_name}.copy_from(&other.gecko.${gecko_ffi_name});
-    }
-    #[allow(non_snake_case)]
-    pub fn reset_${ident}(&mut self, other: &Self) {
-        self.copy_${ident}_from(other)
-    }
-
-    #[allow(non_snake_case)]
-    pub fn clone_${ident}(&self) -> longhands::${ident}::computed_value::T {
-        use crate::properties::longhands::${ident}::computed_value::T;
-        T::from_gecko_style_coord(&self.gecko.${gecko_ffi_name})
-            .expect("clone for ${ident} failed")
-    }
-</%def>
-
-<%def name="impl_style_sides(ident)">
-    <% gecko_ffi_name = "m" + to_camel_case(ident) %>
-
-    #[allow(non_snake_case)]
-    pub fn set_${ident}(&mut self, v: longhands::${ident}::computed_value::T) {
-        v.to_gecko_rect(&mut self.gecko.${gecko_ffi_name});
-    }
-
-    <%self:copy_sides_style_coord ident="${ident}"></%self:copy_sides_style_coord>
-
-    #[allow(non_snake_case)]
-    pub fn clone_${ident}(&self) -> longhands::${ident}::computed_value::T {
-        longhands::${ident}::computed_value::T::from_gecko_rect(&self.gecko.${gecko_ffi_name})
-            .expect("clone for ${ident} failed")
-    }
-</%def>
-
 <%def name="copy_sides_style_coord(ident)">
     <% gecko_ffi_name = "m" + to_camel_case(ident) %>
     #[allow(non_snake_case)]
@@ -812,281 +774,6 @@ def set_gecko_property(ffi_name, expr):
     }
 </%def>
 
-<%
-transform_functions = [
-    ("Matrix3D", "matrix3d", ["number"] * 16),
-    ("Matrix", "matrix", ["number"] * 6),
-    ("Translate", "translate", ["lp", "lp"]),
-    ("Translate3D", "translate3d", ["lp", "lp", "length"]),
-    ("TranslateX", "translatex", ["lp"]),
-    ("TranslateY", "translatey", ["lp"]),
-    ("TranslateZ", "translatez", ["length"]),
-    ("Scale3D", "scale3d", ["number"] * 3),
-    ("Scale", "scale", ["number", "number"]),
-    ("ScaleX", "scalex", ["number"]),
-    ("ScaleY", "scaley", ["number"]),
-    ("ScaleZ", "scalez", ["number"]),
-    ("Rotate", "rotate", ["angle"]),
-    ("Rotate3D", "rotate3d", ["number"] * 3 + ["angle"]),
-    ("RotateX", "rotatex", ["angle"]),
-    ("RotateY", "rotatey", ["angle"]),
-    ("RotateZ", "rotatez", ["angle"]),
-    ("Skew", "skew", ["angle", "angle"]),
-    ("SkewX", "skewx", ["angle"]),
-    ("SkewY", "skewy", ["angle"]),
-    ("Perspective", "perspective", ["length"]),
-    ("InterpolateMatrix", "interpolatematrix", ["list"] * 2 + ["percentage"]),
-    ("AccumulateMatrix", "accumulatematrix", ["list"] * 2 + ["integer_to_percentage"])
-]
-%>
-
-<%def name="transform_function_arm(name, keyword, items)">
-    <%
-        pattern = None
-        if keyword == "matrix3d":
-            # m11: number1, m12: number2, ..
-            single_patterns = ["m%s: %s" % (str(a / 4 + 1) + str(a % 4 + 1), b + str(a + 1)) for (a, b)
-                                in enumerate(items)]
-            pattern = "(Matrix3D { %s })" % ", ".join(single_patterns)
-        elif keyword == "matrix":
-            # a: number1, b: number2, ..
-            single_patterns = ["%s: %s" % (chr(ord('a') + a), b + str(a + 1)) for (a, b)
-                                in enumerate(items)]
-            pattern = "(Matrix { %s })" % ", ".join(single_patterns)
-        elif keyword == "interpolatematrix":
-            pattern = " { from_list: ref list1, to_list: ref list2, progress: percentage3 }"
-        elif keyword == "accumulatematrix":
-            pattern = " { from_list: ref list1, to_list: ref list2, count: integer_to_percentage3 }"
-        else:
-            # Generate contents of pattern from items
-            pattern = "(%s)" % ", ".join([b + str(a+1) for (a,b) in enumerate(items)])
-
-        # First %s substituted with the call to GetArrayItem, the second
-        # %s substituted with the corresponding variable
-        css_value_setters = {
-            "length" : "bindings::Gecko_CSSValue_SetPixelLength(%s, %s.px())",
-            "percentage" : "bindings::Gecko_CSSValue_SetPercentage(%s, %s.0)",
-            # Note: This is an integer type, but we use it as a percentage value in Gecko, so
-            #       need to cast it to f32.
-            "integer_to_percentage" : "bindings::Gecko_CSSValue_SetPercentage(%s, %s as f32)",
-            "lp" : "%s.set_length_percentage(%s)",
-            "angle" : "%s.set_angle(%s)",
-            "number" : "bindings::Gecko_CSSValue_SetNumber(%s, %s)",
-            # Note: We use nsCSSValueSharedList here, instead of nsCSSValueList_heap
-            #       because this function is not called on the main thread and
-            #       nsCSSValueList_heap is not thread safe.
-            "list" : "%s.set_shared_list(%s.0.iter().map(&convert_to_ns_css_value));",
-        }
-    %>
-    crate::values::generics::transform::TransformOperation::${name}${pattern} => {
-        let len = ${len(items) + 1};
-        bindings::Gecko_CSSValue_SetFunction(gecko_value, len);
-        bindings::Gecko_CSSValue_SetKeyword(
-            bindings::Gecko_CSSValue_GetArrayItem(gecko_value, 0),
-            structs::nsCSSKeyword::eCSSKeyword_${keyword}
-        );
-        % for index, item in enumerate(items):
-            % if item == "list":
-                debug_assert!(!${item}${index + 1}.0.is_empty());
-            % endif
-            ${css_value_setters[item] % (
-                "(&mut *bindings::Gecko_CSSValue_GetArrayItem(gecko_value, %d))" % (index + 1),
-                item + str(index + 1)
-            )};
-        % endfor
-    }
-</%def>
-
-<%def name="computed_operation_arm(name, keyword, items)">
-    <%
-        # %s is substituted with the call to GetArrayItem.
-        css_value_getters = {
-            "length" : "Length::new(bindings::Gecko_CSSValue_GetNumber(%s))",
-            "lp" : "%s.get_length_percentage()",
-            "angle" : "%s.get_angle()",
-            "number" : "bindings::Gecko_CSSValue_GetNumber(%s)",
-            "percentage" : "Percentage(bindings::Gecko_CSSValue_GetPercentage(%s))",
-            "integer_to_percentage" : "bindings::Gecko_CSSValue_GetPercentage(%s) as i32",
-            "list" : "Transform(convert_shared_list_to_operations(%s))",
-        }
-        pre_symbols = "("
-        post_symbols = ")"
-        if keyword == "interpolatematrix" or keyword == "accumulatematrix":
-            # We generate this like: "TransformOperation::InterpolateMatrix {", so the space is
-            # between "InterpolateMatrix"/"AccumulateMatrix" and '{'
-            pre_symbols = " {"
-            post_symbols = "}"
-        elif keyword == "matrix3d":
-            pre_symbols = "(Matrix3D {"
-            post_symbols = "})"
-        elif keyword == "matrix":
-            pre_symbols = "(Matrix {"
-            post_symbols = "})"
-        field_names = None
-        if keyword == "interpolatematrix":
-            field_names = ["from_list", "to_list", "progress"]
-        elif keyword == "accumulatematrix":
-            field_names = ["from_list", "to_list", "count"]
-
-    %>
-    structs::nsCSSKeyword::eCSSKeyword_${keyword} => {
-        crate::values::generics::transform::TransformOperation::${name}${pre_symbols}
-        % for index, item in enumerate(items):
-            % if keyword == "matrix3d":
-                m${index / 4 + 1}${index % 4 + 1}:
-            % elif keyword == "matrix":
-                ${chr(ord('a') + index)}:
-            % elif keyword == "interpolatematrix" or keyword == "accumulatematrix":
-                ${field_names[index]}:
-            % endif
-            <%
-                getter = css_value_getters[item] % (
-                    "(&*bindings::Gecko_CSSValue_GetArrayItemConst(gecko_value, %d))" % (index + 1)
-                )
-            %>
-            ${getter},
-        % endfor
-        ${post_symbols}
-    },
-</%def>
-
-#[allow(unused_parens)]
-fn set_single_transform_function(
-    servo_value: &values::computed::TransformOperation,
-    gecko_value: &mut structs::nsCSSValue /* output */
-) {
-    use crate::values::computed::TransformOperation;
-    use crate::values::generics::transform::{Matrix, Matrix3D};
-
-    let convert_to_ns_css_value = |item: &TransformOperation| -> structs::nsCSSValue {
-        let mut value = structs::nsCSSValue::null();
-        set_single_transform_function(item, &mut value);
-        value
-    };
-
-    unsafe {
-        match *servo_value {
-            % for servo, gecko, format in transform_functions:
-                ${transform_function_arm(servo, gecko, format)}
-            % endfor
-        }
-    }
-}
-
-pub fn convert_transform(
-    input: &[values::computed::TransformOperation],
-    output: &mut structs::root::RefPtr<structs::root::nsCSSValueSharedList>
-) {
-    use crate::gecko_bindings::sugar::refptr::RefPtr;
-
-    unsafe { output.clear() };
-
-    let list = unsafe {
-        RefPtr::from_addrefed(bindings::Gecko_NewCSSValueSharedList(input.len() as u32))
-    };
-    let value_list = unsafe { list.mHead.as_mut() };
-    if let Some(value_list) = value_list {
-        for (gecko, servo) in value_list.into_iter().zip(input.into_iter()) {
-            set_single_transform_function(servo, gecko);
-        }
-    }
-    output.set_move(list);
-}
-
-#[allow(unused_parens)]
-fn clone_single_transform_function(
-    gecko_value: &structs::nsCSSValue
-) -> values::computed::TransformOperation {
-    use crate::values::computed::{Length, Percentage, TransformOperation};
-    use crate::values::generics::transform::{Matrix, Matrix3D};
-    use crate::values::generics::transform::Transform;
-
-    let convert_shared_list_to_operations = |value: &structs::nsCSSValue|
-                                            -> Vec<TransformOperation> {
-        debug_assert_eq!(value.mUnit, structs::nsCSSUnit::eCSSUnit_SharedList);
-        let value_list = unsafe {
-            value.mValue.mSharedList.as_ref()
-                    .as_mut().expect("List pointer should be non-null").mHead.as_ref()
-        };
-        debug_assert!(value_list.is_some(), "An empty shared list is not allowed");
-        value_list.unwrap().into_iter()
-                            .map(|item| clone_single_transform_function(item))
-                            .collect()
-    };
-
-    let transform_function = unsafe {
-        bindings::Gecko_CSSValue_GetKeyword(bindings::Gecko_CSSValue_GetArrayItemConst(gecko_value, 0))
-    };
-
-    unsafe {
-        match transform_function {
-            % for servo, gecko, format in transform_functions:
-                ${computed_operation_arm(servo, gecko, format)}
-            % endfor
-            _ => panic!("unacceptable transform function"),
-        }
-    }
-}
-
-pub fn clone_transform_from_list(
-    list: Option< &structs::root::nsCSSValueList>
-) -> values::computed::Transform {
-    use crate::values::generics::transform::Transform;
-
-    let result = match list {
-        Some(list) => {
-            list.into_iter()
-                .filter_map(|value| {
-                    // Handle none transform.
-                    if value.is_none() {
-                        None
-                    } else {
-                        Some(clone_single_transform_function(value))
-                    }
-                })
-                .collect::<Vec<_>>()
-        },
-        _ => vec![],
-    };
-    Transform(result)
-}
-
-<%def name="impl_transform(ident, gecko_ffi_name)">
-    #[allow(non_snake_case)]
-    pub fn set_${ident}(&mut self, other: values::computed::Transform) {
-        use crate::gecko_properties::convert_transform;
-        if other.0.is_empty() {
-            unsafe {
-                self.gecko.${gecko_ffi_name}.clear();
-            }
-            return;
-        };
-        convert_transform(&other.0, &mut self.gecko.${gecko_ffi_name});
-    }
-
-    #[allow(non_snake_case)]
-    pub fn copy_${ident}_from(&mut self, other: &Self) {
-        unsafe { self.gecko.${gecko_ffi_name}.set(&other.gecko.${gecko_ffi_name}); }
-    }
-
-    #[allow(non_snake_case)]
-    pub fn reset_${ident}(&mut self, other: &Self) {
-        self.copy_${ident}_from(other)
-    }
-
-    #[allow(non_snake_case)]
-    pub fn clone_${ident}(&self) -> values::computed::Transform {
-        use crate::gecko_properties::clone_transform_from_list;
-        use crate::values::generics::transform::Transform;
-
-        if self.gecko.${gecko_ffi_name}.mRawPtr.is_null() {
-            return Transform(vec!());
-        }
-        let list = unsafe { (*self.gecko.${gecko_ffi_name}.to_safe().get()).mHead.as_ref() };
-        clone_transform_from_list(list)
-    }
-</%def>
-
 <%def name="impl_logical(name, **kwargs)">
     ${helpers.logical_setter(name)}
 </%def>
@@ -1095,10 +782,10 @@ pub fn clone_transform_from_list(
 impl ${style_struct.gecko_struct_name} {
     #[allow(dead_code, unused_variables)]
     pub fn default(document: &structs::Document) -> Arc<Self> {
-        let mut result = Arc::new(${style_struct.gecko_struct_name} { gecko: unsafe { zeroed() } });
+        let mut result = Arc::new(${style_struct.gecko_struct_name} { gecko: ManuallyDrop::new(unsafe { zeroed() }) });
         unsafe {
             Gecko_Construct_Default_${style_struct.gecko_ffi_name}(
-                &mut Arc::get_mut(&mut result).unwrap().gecko,
+                &mut *Arc::get_mut(&mut result).unwrap().gecko,
                 document,
             );
         }
@@ -1108,15 +795,15 @@ impl ${style_struct.gecko_struct_name} {
 impl Drop for ${style_struct.gecko_struct_name} {
     fn drop(&mut self) {
         unsafe {
-            Gecko_Destroy_${style_struct.gecko_ffi_name}(&mut self.gecko);
+            Gecko_Destroy_${style_struct.gecko_ffi_name}(&mut *self.gecko);
         }
     }
 }
 impl Clone for ${style_struct.gecko_struct_name} {
     fn clone(&self) -> Self {
         unsafe {
-            let mut result = ${style_struct.gecko_struct_name} { gecko: zeroed() };
-            Gecko_CopyConstruct_${style_struct.gecko_ffi_name}(&mut result.gecko, &self.gecko);
+            let mut result = ${style_struct.gecko_struct_name} { gecko: ManuallyDrop::new(zeroed()) };
+            Gecko_CopyConstruct_${style_struct.gecko_ffi_name}(&mut *result.gecko, &*self.gecko);
             result
         }
     }
@@ -1192,7 +879,6 @@ impl Clone for ${style_struct.gecko_struct_name} {
         "SVGOpacity": impl_svg_opacity,
         "SVGPaint": impl_svg_paint,
         "SVGWidth": impl_svg_length,
-        "Transform": impl_transform,
         "url::UrlOrNone": impl_css_url,
     }
 
@@ -1266,7 +952,7 @@ fn static_assert() {
 
 <%self:impl_trait style_struct_name="Border"
                   skip_longhands="${skip_border_longhands} border-image-source
-                                  border-image-repeat border-image-width">
+                                  border-image-repeat">
     % for side in SIDES:
     pub fn set_border_${side.ident}_style(&mut self, v: BorderStyle) {
         self.gecko.mBorderStyle[${side.index}] = v;
@@ -1405,8 +1091,6 @@ fn static_assert() {
         % endfor
         longhands::border_image_repeat::computed_value::T(servo_h, servo_v)
     }
-
-    <% impl_style_sides("border_image_width") %>
 </%self:impl_trait>
 
 <% skip_scroll_margin_longhands = " ".join(["scroll-margin-%s" % x.ident for x in SIDES]) %>
@@ -1545,8 +1229,9 @@ fn static_assert() {
 
     % for kind in ["rows", "columns"]:
     pub fn set_grid_auto_${kind}(&mut self, v: longhands::grid_auto_${kind}::computed_value::T) {
-        v.to_gecko_style_coords(&mut self.gecko.mGridAuto${kind.title()}Min,
-                                &mut self.gecko.mGridAuto${kind.title()}Max)
+        let gecko = &mut *self.gecko;
+        v.to_gecko_style_coords(&mut gecko.mGridAuto${kind.title()}Min,
+                                &mut gecko.mGridAuto${kind.title()}Max)
     }
 
     pub fn copy_grid_auto_${kind}_from(&mut self, other: &Self) {
@@ -1566,14 +1251,14 @@ fn static_assert() {
     pub fn set_grid_template_${kind}(&mut self, v: longhands::grid_template_${kind}::computed_value::T) {
         <% self_grid = "self.gecko.mGridTemplate%s" % kind.title() %>
         use crate::gecko_bindings::structs::{nsTArray, nsStyleGridLine_kMaxLine};
-        use nsstring::nsStringRepr;
+        use nsstring::nsString;
         use std::usize;
         use crate::values::CustomIdent;
         use crate::values::generics::grid::TrackListType::Auto;
         use crate::values::generics::grid::{GridTemplateComponent, RepeatCount};
 
         #[inline]
-        fn set_line_names(servo_names: &[CustomIdent], gecko_names: &mut nsTArray<nsStringRepr>) {
+        fn set_line_names(servo_names: &[CustomIdent], gecko_names: &mut nsTArray<nsString>) {
             unsafe {
                 bindings::Gecko_ResizeTArrayForStrings(gecko_names, servo_names.len() as u32);
             }
@@ -1693,7 +1378,7 @@ fn static_assert() {
     pub fn clone_grid_template_${kind}(&self) -> longhands::grid_template_${kind}::computed_value::T {
         <% self_grid = "self.gecko.mGridTemplate%s" % kind.title() %>
         use crate::gecko_bindings::structs::nsTArray;
-        use nsstring::nsStringRepr;
+        use nsstring::nsString;
         use crate::values::CustomIdent;
         use crate::values::generics::grid::{GridTemplateComponent, LineNameList, RepeatCount};
         use crate::values::generics::grid::{TrackList, TrackListType, TrackListValue, TrackRepeat, TrackSize};
@@ -1704,7 +1389,7 @@ fn static_assert() {
         };
 
         #[inline]
-        fn to_boxed_customident_slice(gecko_names: &nsTArray<nsStringRepr>) -> Box<[CustomIdent]> {
+        fn to_boxed_customident_slice(gecko_names: &nsTArray<nsString>) -> Box<[CustomIdent]> {
             let idents: Vec<CustomIdent> = gecko_names.iter().map(|gecko_name| {
                 CustomIdent(Atom::from(gecko_name.to_string()))
             }).collect();
@@ -1712,7 +1397,7 @@ fn static_assert() {
         }
 
         #[inline]
-        fn to_line_names_vec(gecko_line_names: &nsTArray<nsTArray<nsStringRepr>>)
+        fn to_line_names_vec(gecko_line_names: &nsTArray<nsTArray<nsString>>)
             -> Vec<Box<[CustomIdent]>> {
             gecko_line_names.iter().map(|gecko_names| {
                 to_boxed_customident_slice(gecko_names)
@@ -2129,14 +1814,14 @@ fn static_assert() {
         let ptr = v.0.as_ptr();
         forget(v);
         unsafe {
-            Gecko_nsStyleFont_SetLang(&mut self.gecko, ptr);
+            Gecko_nsStyleFont_SetLang(&mut *self.gecko, ptr);
         }
     }
 
     #[allow(non_snake_case)]
     pub fn copy__x_lang_from(&mut self, other: &Self) {
         unsafe {
-            Gecko_nsStyleFont_CopyLangFrom(&mut self.gecko, &other.gecko);
+            Gecko_nsStyleFont_CopyLangFrom(&mut *self.gecko, &*other.gecko);
         }
     }
 
@@ -2473,56 +2158,16 @@ fn static_assert() {
     ${impl_copy_animation_value(ident, gecko_ffi_name)}
 </%def>
 
-<%def name="impl_individual_transform(ident, type, gecko_ffi_name)">
-    pub fn set_${ident}(&mut self, other: values::computed::${type}) {
-        unsafe { self.gecko.${gecko_ffi_name}.clear() };
-
-        if let Some(operation) = other.to_transform_operation() {
-            convert_transform(&[operation], &mut self.gecko.${gecko_ffi_name})
-        }
-    }
-
-    pub fn copy_${ident}_from(&mut self, other: &Self) {
-        unsafe { self.gecko.${gecko_ffi_name}.set(&other.gecko.${gecko_ffi_name}); }
-    }
-
-    pub fn reset_${ident}(&mut self, other: &Self) {
-        self.copy_${ident}_from(other)
-    }
-
-    pub fn clone_${ident}(&self) -> values::computed::${type} {
-        use crate::values::generics::transform::${type};
-
-        if self.gecko.${gecko_ffi_name}.mRawPtr.is_null() {
-            return ${type}::None;
-        }
-
-        let list = unsafe { (*self.gecko.${gecko_ffi_name}.to_safe().get()).mHead.as_ref() };
-
-        let mut transform = clone_transform_from_list(list);
-        debug_assert_eq!(transform.0.len(), 1);
-        ${type}::from_transform_operation(&transform.0.pop().unwrap())
-    }
-</%def>
-
 <% skip_box_longhands= """display
                           animation-name animation-delay animation-duration
                           animation-direction animation-fill-mode animation-play-state
                           animation-iteration-count animation-timing-function
                           clear transition-duration transition-delay
                           transition-timing-function transition-property
-                          transform-style
-                          rotate scroll-snap-points-x scroll-snap-points-y
-                          scroll-snap-coordinate -moz-binding will-change
-                          offset-path shape-outside
-                          translate scale -webkit-line-clamp""" %>
+                          transform-style -moz-binding shape-outside
+                          -webkit-line-clamp""" %>
 <%self:impl_trait style_struct_name="Box" skip_longhands="${skip_box_longhands}">
     #[inline]
-    pub fn generate_combined_transform(&mut self) {
-        unsafe { bindings::Gecko_StyleDisplay_GenerateCombinedTransform(&mut self.gecko) };
-    }
-
-    #[inline]
     pub fn set_display(&mut self, v: longhands::display::computed_value::T) {
         self.gecko.mDisplay = v;
         self.gecko.mOriginalDisplay = v;
@@ -2560,33 +2205,7 @@ fn static_assert() {
         gecko_inexhaustive=True,
     ) %>
     ${impl_keyword('clear', 'mBreakType', clear_keyword)}
-
-    ${impl_style_coord("scroll_snap_points_x", "mScrollSnapPointsX")}
-    ${impl_style_coord("scroll_snap_points_y", "mScrollSnapPointsY")}
-
-    pub fn set_scroll_snap_coordinate<I>(&mut self, v: I)
-        where I: IntoIterator<Item = longhands::scroll_snap_coordinate::computed_value::single_value::T>,
-              I::IntoIter: ExactSizeIterator
-    {
-        self.gecko.mScrollSnapCoordinate.assign_from_iter_pod(v.into_iter());
-    }
-
-    pub fn copy_scroll_snap_coordinate_from(&mut self, other: &Self) {
-        let iter = other.gecko.mScrollSnapCoordinate.iter().map(|c| *c);
-        self.gecko.mScrollSnapCoordinate.assign_from_iter_pod(iter);
-    }
-
-    pub fn reset_scroll_snap_coordinate(&mut self, other: &Self) {
-        self.copy_scroll_snap_coordinate_from(other)
-    }
-
-    pub fn clone_scroll_snap_coordinate(&self) -> longhands::scroll_snap_coordinate::computed_value::T {
-        let vec = self.gecko.mScrollSnapCoordinate.iter().cloned().collect();
-        longhands::scroll_snap_coordinate::computed_value::List(vec)
-    }
-
     ${impl_css_url('_moz_binding', 'mBinding')}
-
     ${impl_transition_time_value('delay', 'Delay')}
     ${impl_transition_time_value('duration', 'Duration')}
     ${impl_transition_timing_function()}
@@ -2825,105 +2444,8 @@ fn static_assert() {
 
     ${impl_animation_timing_function()}
 
-    ${impl_individual_transform('rotate', 'Rotate', 'mSpecifiedRotate')}
-    ${impl_individual_transform('translate', 'Translate', 'mSpecifiedTranslate')}
-    ${impl_individual_transform('scale', 'Scale', 'mSpecifiedScale')}
-
-    pub fn set_will_change(&mut self, v: longhands::will_change::computed_value::T) {
-        use crate::gecko_bindings::bindings::{Gecko_AppendWillChange, Gecko_ClearWillChange};
-        use crate::values::specified::box_::{WillChangeBits, WillChange};
-
-        match v {
-            WillChange::AnimateableFeatures { features, bits } => {
-                unsafe {
-                    Gecko_ClearWillChange(&mut self.gecko, features.len());
-                }
-
-                for feature in features.iter() {
-                    unsafe {
-                        Gecko_AppendWillChange(&mut self.gecko, feature.0.as_ptr())
-                    }
-                }
-
-                self.gecko.mWillChangeBitField = bits;
-            },
-            WillChange::Auto => {
-                unsafe {
-                    Gecko_ClearWillChange(&mut self.gecko, 0);
-                }
-                self.gecko.mWillChangeBitField = WillChangeBits::empty();
-            },
-        };
-    }
-
-    pub fn copy_will_change_from(&mut self, other: &Self) {
-        use crate::gecko_bindings::bindings::Gecko_CopyWillChangeFrom;
-
-        self.gecko.mWillChangeBitField = other.gecko.mWillChangeBitField;
-        unsafe {
-            Gecko_CopyWillChangeFrom(&mut self.gecko, &other.gecko);
-        }
-    }
-
-    pub fn reset_will_change(&mut self, other: &Self) {
-        self.copy_will_change_from(other)
-    }
-
-    pub fn clone_will_change(&self) -> longhands::will_change::computed_value::T {
-        use crate::values::CustomIdent;
-        use crate::values::specified::box_::WillChange;
-
-        if self.gecko.mWillChange.len() == 0 {
-            return WillChange::Auto
-        }
-
-        let custom_idents: Vec<CustomIdent> = self.gecko.mWillChange.iter().map(|gecko_atom| {
-            unsafe {
-                CustomIdent(Atom::from_raw(gecko_atom.mRawPtr))
-            }
-        }).collect();
-
-        WillChange::AnimateableFeatures {
-            features: custom_idents.into_boxed_slice(),
-            bits: self.gecko.mWillChangeBitField,
-        }
-    }
-
     <% impl_shape_source("shape_outside", "mShapeOutside") %>
 
-    pub fn set_offset_path(&mut self, v: longhands::offset_path::computed_value::T) {
-        use crate::gecko_bindings::bindings::{Gecko_NewStyleMotion, Gecko_SetStyleMotion};
-        use crate::gecko_bindings::structs::StyleShapeSourceType;
-        use crate::values::generics::basic_shape::FillRule;
-        use crate::values::specified::OffsetPath;
-
-        let motion = unsafe { Gecko_NewStyleMotion().as_mut().unwrap() };
-        match v {
-            OffsetPath::None => motion.mOffsetPath.mType = StyleShapeSourceType::None,
-            OffsetPath::Path(p) => {
-                set_style_svg_path(&mut motion.mOffsetPath, p, FillRule::Nonzero)
-            },
-        }
-        unsafe { Gecko_SetStyleMotion(&mut self.gecko.mMotion, motion) };
-    }
-
-    pub fn clone_offset_path(&self) -> longhands::offset_path::computed_value::T {
-        use crate::values::specified::OffsetPath;
-        match unsafe { self.gecko.mMotion.mPtr.as_ref() } {
-            None => OffsetPath::none(),
-            Some(v) => (&v.mOffsetPath).into()
-        }
-    }
-
-    pub fn copy_offset_path_from(&mut self, other: &Self) {
-        use crate::gecko_bindings::bindings::Gecko_CopyStyleMotions;
-        unsafe { Gecko_CopyStyleMotions(&mut self.gecko.mMotion, other.gecko.mMotion.mPtr) };
-    }
-
-    pub fn reset_offset_path(&mut self, other: &Self) {
-        self.copy_offset_path_from(other);
-    }
-
     #[allow(non_snake_case)]
     pub fn set__webkit_line_clamp(&mut self, v: longhands::_webkit_line_clamp::computed_value::T) {
         self.gecko.mLineClamp = match v {
@@ -3301,19 +2823,19 @@ fn static_assert() {
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="List"
-                  skip_longhands="list-style-image list-style-type quotes -moz-image-region">
+                  skip_longhands="list-style-image list-style-type -moz-image-region">
 
     pub fn set_list_style_image(&mut self, image: longhands::list_style_image::computed_value::T) {
         match image {
             UrlOrNone::None => {
                 unsafe {
-                    Gecko_SetListStyleImageNone(&mut self.gecko);
+                    Gecko_SetListStyleImageNone(&mut *self.gecko);
                 }
             }
             UrlOrNone::Url(ref url) => {
                 unsafe {
                     Gecko_SetListStyleImageImageValue(
-                        &mut self.gecko,
+                        &mut *self.gecko,
                         url.url_value_ptr(),
                     );
                 }
@@ -3322,7 +2844,7 @@ fn static_assert() {
     }
 
     pub fn copy_list_style_image_from(&mut self, other: &Self) {
-        unsafe { Gecko_CopyListStyleImageFrom(&mut self.gecko, &other.gecko); }
+        unsafe { Gecko_CopyListStyleImageFrom(&mut *self.gecko, &*other.gecko); }
     }
 
     pub fn reset_list_style_image(&mut self, other: &Self) {
@@ -3330,8 +2852,6 @@ fn static_assert() {
     }
 
     pub fn clone_list_style_image(&self) -> longhands::list_style_image::computed_value::T {
-        use crate::values::computed::url::ComputedImageUrl;
-
         if self.gecko.mListStyleImage.mRawPtr.is_null() {
             return UrlOrNone::None;
         }
@@ -3377,28 +2897,6 @@ fn static_assert() {
         }
     }
 
-    pub fn set_quotes(&mut self, other: longhands::quotes::computed_value::T) {
-        self.gecko.mQuotes.set_arc(other.0.clone());
-    }
-
-    pub fn copy_quotes_from(&mut self, other: &Self) {
-        self.set_quotes(other.clone_quotes());
-    }
-
-    pub fn reset_quotes(&mut self, other: &Self) {
-        self.copy_quotes_from(other)
-    }
-
-    pub fn clone_quotes(&self) -> longhands::quotes::computed_value::T {
-        use gecko_bindings::sugar::ownership::HasArcFFI;
-        use values::computed::QuotePair;
-
-        let quote_pairs = unsafe { &*self.gecko.mQuotes.mRawPtr };
-        longhands::quotes::computed_value::T(
-            Box::<[QuotePair]>::as_arc(&quote_pairs).clone_arc()
-        )
-    }
-
     #[allow(non_snake_case)]
     pub fn set__moz_image_region(&mut self, v: longhands::_moz_image_region::computed_value::T) {
         use crate::values::Either;
@@ -3476,31 +2974,7 @@ fn static_assert() {
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="Effects"
-                  skip_longhands="box-shadow clip filter">
-    pub fn set_box_shadow<I>(&mut self, v: I)
-        where I: IntoIterator<Item = BoxShadow>,
-              I::IntoIter: ExactSizeIterator
-    {
-        let v = v.into_iter();
-        self.gecko.mBoxShadow.replace_with_new(v.len() as u32);
-        for (servo, gecko_shadow) in v.zip(self.gecko.mBoxShadow.iter_mut()) {
-            gecko_shadow.set_from_box_shadow(servo);
-        }
-    }
-
-    pub fn copy_box_shadow_from(&mut self, other: &Self) {
-        self.gecko.mBoxShadow.copy_from(&other.gecko.mBoxShadow);
-    }
-
-    pub fn reset_box_shadow(&mut self, other: &Self) {
-        self.copy_box_shadow_from(other)
-    }
-
-    pub fn clone_box_shadow(&self) -> longhands::box_shadow::computed_value::T {
-        let buf = self.gecko.mBoxShadow.iter().map(|v| v.to_box_shadow()).collect();
-        longhands::box_shadow::computed_value::List(buf)
-    }
-
+                  skip_longhands="clip filter">
     pub fn set_clip(&mut self, v: longhands::clip::computed_value::T) {
         use crate::gecko_bindings::structs::NS_STYLE_CLIP_AUTO;
         use crate::gecko_bindings::structs::NS_STYLE_CLIP_RECT;
@@ -3624,7 +3098,6 @@ fn static_assert() {
         I::IntoIter: ExactSizeIterator,
     {
         use crate::values::generics::effects::Filter::*;
-        use crate::gecko_bindings::structs::nsCSSShadowArray;
         use crate::gecko_bindings::structs::nsStyleFilter;
         use crate::gecko_bindings::structs::NS_STYLE_FILTER_BLUR;
         use crate::gecko_bindings::structs::NS_STYLE_FILTER_BRIGHTNESS;
@@ -3644,7 +3117,7 @@ fn static_assert() {
 
         let v = v.into_iter();
         unsafe {
-            Gecko_ResetFilters(&mut self.gecko, v.len());
+            Gecko_ResetFilters(&mut *self.gecko, v.len());
         }
         debug_assert_eq!(v.len(), self.gecko.mFilters.len());
 
@@ -3665,19 +3138,10 @@ fn static_assert() {
 
                 DropShadow(shadow) => {
                     gecko_filter.mType = NS_STYLE_FILTER_DROP_SHADOW;
-
-                    fn init_shadow(filter: &mut nsStyleFilter) -> &mut nsCSSShadowArray {
-                        unsafe {
-                            let ref mut union = filter.__bindgen_anon_1;
-                            let shadow_array: &mut *mut nsCSSShadowArray = union.mDropShadow.as_mut();
-                            *shadow_array = Gecko_NewCSSShadowArray(1);
-
-                            &mut **shadow_array
-                        }
+                    unsafe {
+                        let ref mut union = gecko_filter.__bindgen_anon_1;
+                        ptr::write(union.mDropShadow.as_mut(), shadow);
                     }
-
-                    let gecko_shadow = init_shadow(gecko_filter);
-                    gecko_shadow.mArray[0].set_from_simple_shadow(shadow);
                 },
                 Url(ref url) => {
                     unsafe {
@@ -3690,7 +3154,7 @@ fn static_assert() {
 
     pub fn copy_filter_from(&mut self, other: &Self) {
         unsafe {
-            Gecko_CopyFiltersFrom(&other.gecko as *const _ as *mut _, &mut self.gecko);
+            Gecko_CopyFiltersFrom(&other.gecko as *const _ as *mut _, &mut *self.gecko);
         }
     }
 
@@ -3713,42 +3177,41 @@ fn static_assert() {
         use crate::gecko_bindings::structs::NS_STYLE_FILTER_DROP_SHADOW;
         use crate::gecko_bindings::structs::NS_STYLE_FILTER_URL;
 
-        let mut filters = Vec::new();
-        for filter in self.gecko.mFilters.iter(){
+        longhands::filter::computed_value::List(self.gecko.mFilters.iter().map(|filter| {
             match filter.mType {
                 % for func in FILTER_FUNCTIONS:
                 NS_STYLE_FILTER_${func.upper()} => {
-                    filters.push(Filter::${func}(
+                    Filter::${func}(
                         GeckoStyleCoordConvertible::from_gecko_style_coord(
-                            &filter.mFilterParameter).unwrap()));
+                            &filter.mFilterParameter
+                        ).unwrap()
+                    )
                 },
                 % endfor
                 NS_STYLE_FILTER_BLUR => {
-                    filters.push(Filter::Blur(NonNegativeLength::from_gecko_style_coord(
-                        &filter.mFilterParameter).unwrap()));
+                    Filter::Blur(NonNegativeLength::from_gecko_style_coord(
+                        &filter.mFilterParameter
+                    ).unwrap())
                 },
                 NS_STYLE_FILTER_HUE_ROTATE => {
-                    filters.push(Filter::HueRotate(
-                        GeckoStyleCoordConvertible::from_gecko_style_coord(
-                            &filter.mFilterParameter).unwrap()));
+                    Filter::HueRotate(GeckoStyleCoordConvertible::from_gecko_style_coord(
+                        &filter.mFilterParameter,
+                    ).unwrap())
                 },
                 NS_STYLE_FILTER_DROP_SHADOW => {
-                    filters.push(unsafe {
-                        Filter::DropShadow(
-                            (**filter.__bindgen_anon_1.mDropShadow.as_ref()).mArray[0].to_simple_shadow(),
-                        )
-                    });
+                    Filter::DropShadow(unsafe {
+                        (*filter.__bindgen_anon_1.mDropShadow.as_ref()).clone()
+                    })
                 },
                 NS_STYLE_FILTER_URL => {
-                    filters.push(Filter::Url(unsafe {
+                    Filter::Url(unsafe {
                         let url = RefPtr::new(*filter.__bindgen_anon_1.mURL.as_ref());
                         ComputedUrl::from_url_value(url)
-                    }));
+                    })
                 }
-                _ => {},
+                _ => unreachable!("Unknown filter function?"),
             }
-        }
-        longhands::filter::computed_value::List(filters)
+        }).collect())
     }
 
 </%self:impl_trait>
@@ -3783,7 +3246,7 @@ fn static_assert() {
 
 
 <%self:impl_trait style_struct_name="InheritedText"
-                  skip_longhands="text-align text-emphasis-style text-shadow
+                  skip_longhands="text-align text-emphasis-style
                                   -webkit-text-stroke-width text-emphasis-position">
 
     <% text_align_keyword = Keyword("text-align",
@@ -3791,30 +3254,6 @@ fn static_assert() {
                                     gecko_strip_moz_prefix=False) %>
     ${impl_keyword('text_align', 'mTextAlign', text_align_keyword)}
 
-    pub fn set_text_shadow<I>(&mut self, v: I)
-        where I: IntoIterator<Item = SimpleShadow>,
-              I::IntoIter: ExactSizeIterator
-    {
-        let v = v.into_iter();
-        self.gecko.mTextShadow.replace_with_new(v.len() as u32);
-        for (servo, gecko_shadow) in v.zip(self.gecko.mTextShadow.iter_mut()) {
-            gecko_shadow.set_from_simple_shadow(servo);
-        }
-    }
-
-    pub fn copy_text_shadow_from(&mut self, other: &Self) {
-        self.gecko.mTextShadow.copy_from(&other.gecko.mTextShadow);
-    }
-
-    pub fn reset_text_shadow(&mut self, other: &Self) {
-        self.copy_text_shadow_from(other)
-    }
-
-    pub fn clone_text_shadow(&self) -> longhands::text_shadow::computed_value::T {
-        let buf = self.gecko.mTextShadow.iter().map(|v| v.to_simple_shadow()).collect();
-        longhands::text_shadow::computed_value::List(buf)
-    }
-
     fn clear_text_emphasis_style_if_string(&mut self) {
         if self.gecko.mTextEmphasisStyle == structs::NS_STYLE_TEXT_EMPHASIS_STYLE_STRING as u8 {
             self.gecko.mTextEmphasisStyleString.truncate();
@@ -3903,83 +3342,7 @@ fn static_assert() {
 
 </%self:impl_trait>
 
-<%self:impl_trait style_struct_name="Text"
-                  skip_longhands="text-overflow initial-letter">
-
-    fn clear_overflow_sides_if_string(&mut self) {
-        use crate::gecko_bindings::structs::nsStyleTextOverflowSide;
-        fn clear_if_string(side: &mut nsStyleTextOverflowSide) {
-            if side.mType == structs::NS_STYLE_TEXT_OVERFLOW_STRING as u8 {
-                side.mString.truncate();
-                side.mType = structs::NS_STYLE_TEXT_OVERFLOW_CLIP as u8;
-            }
-        }
-        clear_if_string(&mut self.gecko.mTextOverflow.mLeft);
-        clear_if_string(&mut self.gecko.mTextOverflow.mRight);
-    }
-
-    pub fn set_text_overflow(&mut self, v: longhands::text_overflow::computed_value::T) {
-        use crate::gecko_bindings::structs::nsStyleTextOverflowSide;
-        use crate::values::specified::text::TextOverflowSide;
-
-        fn set(side: &mut nsStyleTextOverflowSide, value: &TextOverflowSide) {
-            let ty = match *value {
-                TextOverflowSide::Clip => structs::NS_STYLE_TEXT_OVERFLOW_CLIP,
-                TextOverflowSide::Ellipsis => structs::NS_STYLE_TEXT_OVERFLOW_ELLIPSIS,
-                TextOverflowSide::String(ref s) => {
-                    side.mString.assign_str(s);
-                    structs::NS_STYLE_TEXT_OVERFLOW_STRING
-                }
-            };
-            side.mType = ty as u8;
-        }
-
-        self.clear_overflow_sides_if_string();
-        self.gecko.mTextOverflow.mLogicalDirections = v.sides_are_logical;
-
-        set(&mut self.gecko.mTextOverflow.mLeft, &v.first);
-        set(&mut self.gecko.mTextOverflow.mRight, &v.second);
-    }
-
-    pub fn copy_text_overflow_from(&mut self, other: &Self) {
-        use crate::gecko_bindings::structs::nsStyleTextOverflowSide;
-        fn set(side: &mut nsStyleTextOverflowSide, other: &nsStyleTextOverflowSide) {
-            if other.mType == structs::NS_STYLE_TEXT_OVERFLOW_STRING as u8 {
-                side.mString.assign(&*other.mString)
-            }
-            side.mType = other.mType
-        }
-        self.clear_overflow_sides_if_string();
-        set(&mut self.gecko.mTextOverflow.mLeft, &other.gecko.mTextOverflow.mLeft);
-        set(&mut self.gecko.mTextOverflow.mRight, &other.gecko.mTextOverflow.mRight);
-        self.gecko.mTextOverflow.mLogicalDirections = other.gecko.mTextOverflow.mLogicalDirections;
-    }
-
-    pub fn reset_text_overflow(&mut self, other: &Self) {
-        self.copy_text_overflow_from(other)
-    }
-
-    pub fn clone_text_overflow(&self) -> longhands::text_overflow::computed_value::T {
-        use crate::gecko_bindings::structs::nsStyleTextOverflowSide;
-        use crate::values::specified::text::TextOverflowSide;
-
-        fn to_servo(side: &nsStyleTextOverflowSide) -> TextOverflowSide {
-            match side.mType as u32 {
-                structs::NS_STYLE_TEXT_OVERFLOW_CLIP => TextOverflowSide::Clip,
-                structs::NS_STYLE_TEXT_OVERFLOW_ELLIPSIS => TextOverflowSide::Ellipsis,
-                structs::NS_STYLE_TEXT_OVERFLOW_STRING =>
-                    TextOverflowSide::String(side.mString.to_string().into_boxed_str()),
-                _ => panic!("Found unexpected value in style struct for text_overflow property"),
-            }
-        }
-
-        longhands::text_overflow::computed_value::T {
-            first: to_servo(&self.gecko.mTextOverflow.mLeft),
-            second: to_servo(&self.gecko.mTextOverflow.mRight),
-            sides_are_logical: self.gecko.mTextOverflow.mLogicalDirections
-        }
-    }
-
+<%self:impl_trait style_struct_name="Text" skip_longhands="initial-letter">
     pub fn set_initial_letter(&mut self, v: longhands::initial_letter::computed_value::T) {
         use crate::values::generics::text::InitialLetter;
         match v {
@@ -4050,25 +3413,19 @@ fn set_style_svg_path(
         ${ident}.mType = StyleShapeSourceType::None;
 
         match v {
-            % if ident == "clip_path":
-            ShapeSource::ImageOrUrl(ref url) => {
-                unsafe {
-                    bindings::Gecko_StyleShapeSource_SetURLValue(${ident}, url.url_value_ptr())
-                }
-            }
-            % elif ident == "shape_outside":
+            ShapeSource::None => {} // don't change the type
             ShapeSource::ImageOrUrl(image) => {
+                % if ident == "clip_path":
+                use crate::values::generics::image::Image;
+
+                let image = Image::Url(ComputedImageUrl(image));
+                % endif
                 unsafe {
                     bindings::Gecko_NewShapeImage(${ident});
                     let style_image = &mut *${ident}.__bindgen_anon_1.mShapeImage.as_mut().mPtr;
                     style_image.set(image);
                 }
             }
-            % else:
-               <% raise Exception("Unknown property: %s" % ident) %>
-            }
-            % endif
-            ShapeSource::None => {} // don't change the type
             ShapeSource::Box(reference) => {
                 ${ident}.mReferenceBox = reference.into();
                 ${ident}.mType = StyleShapeSourceType::Box;
@@ -4118,7 +3475,7 @@ clip-path
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="InheritedSVG"
-                  skip_longhands="paint-order stroke-dasharray -moz-context-properties">
+                  skip_longhands="paint-order stroke-dasharray">
     pub fn set_paint_order(&mut self, v: longhands::paint_order::computed_value::T) {
         self.gecko.mPaintOrder = v.0;
     }
@@ -4139,7 +3496,7 @@ clip-path
                 let v = v.into_iter();
                 self.gecko.mContextFlags &= !CONTEXT_VALUE;
                 unsafe {
-                    bindings::Gecko_nsStyleSVG_SetDashArrayLength(&mut self.gecko, v.len() as u32);
+                    bindings::Gecko_nsStyleSVG_SetDashArrayLength(&mut *self.gecko, v.len() as u32);
                 }
                 for (gecko, servo) in self.gecko.mStrokeDasharray.iter_mut().zip(v) {
                     *gecko = servo;
@@ -4148,7 +3505,7 @@ clip-path
             SVGStrokeDashArray::ContextValue => {
                 self.gecko.mContextFlags |= CONTEXT_VALUE;
                 unsafe {
-                    bindings::Gecko_nsStyleSVG_SetDashArrayLength(&mut self.gecko, 0);
+                    bindings::Gecko_nsStyleSVG_SetDashArrayLength(&mut *self.gecko, 0);
                 }
             }
         }
@@ -4157,7 +3514,7 @@ clip-path
     pub fn copy_stroke_dasharray_from(&mut self, other: &Self) {
         use crate::gecko_bindings::structs::nsStyleSVG_STROKE_DASHARRAY_CONTEXT as CONTEXT_VALUE;
         unsafe {
-            bindings::Gecko_nsStyleSVG_CopyDashArray(&mut self.gecko, &other.gecko);
+            bindings::Gecko_nsStyleSVG_CopyDashArray(&mut *self.gecko, &*other.gecko);
         }
         self.gecko.mContextFlags =
             (self.gecko.mContextFlags & !CONTEXT_VALUE) |
@@ -4178,61 +3535,6 @@ clip-path
         }
         SVGStrokeDashArray::Values(self.gecko.mStrokeDasharray.iter().cloned().collect())
     }
-
-    #[allow(non_snake_case)]
-    pub fn _moz_context_properties_count(&self) -> usize {
-        self.gecko.mContextProps.len()
-    }
-
-    #[allow(non_snake_case)]
-    pub fn _moz_context_properties_at(
-        &self,
-        index: usize,
-    ) -> longhands::_moz_context_properties::computed_value::single_value::T {
-        longhands::_moz_context_properties::computed_value::single_value::T(
-            CustomIdent(unsafe {
-                Atom::from_raw(self.gecko.mContextProps[index].mRawPtr)
-            })
-        )
-    }
-
-    #[allow(non_snake_case)]
-    pub fn set__moz_context_properties<I>(&mut self, v: I)
-    where
-        I: IntoIterator<Item = longhands::_moz_context_properties::computed_value::single_value::T>,
-        I::IntoIter: ExactSizeIterator
-    {
-        let v = v.into_iter();
-        unsafe {
-            bindings::Gecko_nsStyleSVG_SetContextPropertiesLength(&mut self.gecko, v.len() as u32);
-        }
-
-        self.gecko.mContextPropsBits = 0;
-        for (gecko, servo) in self.gecko.mContextProps.iter_mut().zip(v) {
-            if (servo.0).0 == atom!("fill") {
-                self.gecko.mContextPropsBits |= structs::NS_STYLE_CONTEXT_PROPERTY_FILL as u8;
-            } else if (servo.0).0 == atom!("stroke") {
-                self.gecko.mContextPropsBits |= structs::NS_STYLE_CONTEXT_PROPERTY_STROKE as u8;
-            } else if (servo.0).0 == atom!("fill-opacity") {
-                self.gecko.mContextPropsBits |= structs::NS_STYLE_CONTEXT_PROPERTY_FILL_OPACITY as u8;
-            } else if (servo.0).0 == atom!("stroke-opacity") {
-                self.gecko.mContextPropsBits |= structs::NS_STYLE_CONTEXT_PROPERTY_STROKE_OPACITY as u8;
-            }
-            gecko.mRawPtr = (servo.0).0.into_addrefed();
-        }
-    }
-
-    #[allow(non_snake_case)]
-    pub fn copy__moz_context_properties_from(&mut self, other: &Self) {
-        unsafe {
-            bindings::Gecko_nsStyleSVG_CopyContextProperties(&mut self.gecko, &other.gecko);
-        }
-    }
-
-    #[allow(non_snake_case)]
-    pub fn reset__moz_context_properties(&mut self, other: &Self) {
-        self.copy__moz_context_properties_from(other)
-    }
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="Color">
@@ -4242,7 +3544,7 @@ clip-path
     pub fn set_cursor(&mut self, v: longhands::cursor::computed_value::T) {
         self.gecko.mCursor = v.keyword;
         unsafe {
-            Gecko_SetCursorArrayLength(&mut self.gecko, v.images.len());
+            Gecko_SetCursorArrayLength(&mut *self.gecko, v.images.len());
         }
         for i in 0..v.images.len() {
             unsafe {
@@ -4268,7 +3570,7 @@ clip-path
     pub fn copy_cursor_from(&mut self, other: &Self) {
         self.gecko.mCursor = other.gecko.mCursor;
         unsafe {
-            Gecko_CopyCursorArrayFrom(&mut self.gecko, &other.gecko);
+            Gecko_CopyCursorArrayFrom(&mut *self.gecko, &*other.gecko);
         }
     }
 
@@ -4278,7 +3580,6 @@ clip-path
 
     pub fn clone_cursor(&self) -> longhands::cursor::computed_value::T {
         use crate::values::computed::ui::CursorImage;
-        use crate::values::computed::url::ComputedImageUrl;
 
         let keyword = self.gecko.mCursor;
 
@@ -4387,20 +3688,20 @@ clip-path
                 // Ensure destructors run, otherwise we could leak.
                 if !self.gecko.mContents.is_empty() {
                     unsafe {
-                        Gecko_ClearAndResizeStyleContents(&mut self.gecko, 0);
+                        Gecko_ClearAndResizeStyleContents(&mut *self.gecko, 0);
                     }
                 }
             },
             Content::MozAltContent => {
                 unsafe {
-                    Gecko_ClearAndResizeStyleContents(&mut self.gecko, 1);
+                    Gecko_ClearAndResizeStyleContents(&mut *self.gecko, 1);
                     *self.gecko.mContents[0].mContent.mString.as_mut() = ptr::null_mut();
                 }
                 self.gecko.mContents[0].mType = StyleContentType::AltContent;
             },
             Content::Items(items) => {
                 unsafe {
-                    Gecko_ClearAndResizeStyleContents(&mut self.gecko,
+                    Gecko_ClearAndResizeStyleContents(&mut *self.gecko,
                                                       items.len() as u32);
                 }
                 for (i, item) in items.into_vec().into_iter().enumerate() {
@@ -4481,7 +3782,7 @@ clip-path
     pub fn copy_content_from(&mut self, other: &Self) {
         use crate::gecko_bindings::bindings::Gecko_CopyStyleContentsFrom;
         unsafe {
-            Gecko_CopyStyleContentsFrom(&mut self.gecko, &other.gecko)
+            Gecko_CopyStyleContentsFrom(&mut *self.gecko, &*other.gecko)
         }
     }
 
@@ -4494,7 +3795,6 @@ clip-path
         use crate::gecko::conversions::string_from_chars_pointer;
         use crate::gecko_bindings::structs::StyleContentType;
         use crate::values::generics::counters::{Content, ContentItem};
-        use crate::values::computed::url::ComputedImageUrl;
         use crate::values::{CustomIdent, Either};
         use crate::values::generics::CounterStyleOrNone;
         use crate::values::specified::Attr;
@@ -4575,7 +3875,7 @@ clip-path
             v: longhands::counter_${counter_property.lower()}::computed_value::T
         ) {
             unsafe {
-                bindings::Gecko_ClearAndResizeCounter${counter_property}s(&mut self.gecko, v.len() as u32);
+                bindings::Gecko_ClearAndResizeCounter${counter_property}s(&mut *self.gecko, v.len() as u32);
                 for (i, pair) in v.0.into_vec().into_iter().enumerate() {
                     self.gecko.m${counter_property}s[i].mCounter.set_move(
                         RefPtr::from_addrefed(pair.name.0.into_addrefed())
@@ -4587,7 +3887,7 @@ clip-path
 
         pub fn copy_counter_${counter_property.lower()}_from(&mut self, other: &Self) {
             unsafe {
-                bindings::Gecko_CopyCounter${counter_property}sFrom(&mut self.gecko, &other.gecko)
+                bindings::Gecko_CopyCounter${counter_property}sFrom(&mut *self.gecko, &*other.gecko)
             }
         }
 
diff --git a/components/style/properties/helpers.mako.rs b/components/style/properties/helpers.mako.rs
index 8310d537f36..800d50c6220 100644
--- a/components/style/properties/helpers.mako.rs
+++ b/components/style/properties/helpers.mako.rs
@@ -10,7 +10,7 @@
 <%def name="predefined_type(name, type, initial_value, parse_method='parse',
             needs_context=True, vector=False,
             computed_type=None, initial_specified_value=None,
-            allow_quirks=False, allow_empty=False, **kwargs)">
+            allow_quirks='No', allow_empty=False, **kwargs)">
     <%def name="predefined_type_inner(name, type, initial_value, parse_method)">
         #[allow(unused_imports)]
         use app_units::Au;
@@ -42,8 +42,8 @@
             context: &ParserContext,
             input: &mut Parser<'i, 't>,
         ) -> Result<SpecifiedValue, ParseError<'i>> {
-            % if allow_quirks:
-            specified::${type}::${parse_method}_quirky(context, input, AllowQuirks::Yes)
+            % if allow_quirks != "No":
+            specified::${type}::${parse_method}_quirky(context, input, AllowQuirks::${allow_quirks})
             % elif needs_context:
             specified::${type}::${parse_method}(context, input)
             % else:
@@ -80,12 +80,26 @@
     We assume that the default/initial value is an empty vector for these.
     `initial_value` need not be defined for these.
 </%doc>
+
+// The setup here is roughly:
+//
+//  * UnderlyingList is the list that is stored in the computed value. This may
+//    be a shared ArcSlice if the property is inherited.
+//  * UnderlyingOwnedList is the list that is used for animation.
+//  * Specified values always use OwnedSlice, since it's more compact.
+//  * computed_value::List is just a convenient alias that you can use for the
+//    computed value list, since this is in the computed_value module.
+//
+// If simple_vector_bindings is true, then we don't use the complex iterator
+// machinery and set_foo_from, and just compute the value like any other
+// longhand.
 <%def name="vector_longhand(name, animation_value_type=None,
                             vector_animation_type=None, allow_empty=False,
+                            simple_vector_bindings=False,
                             separator='Comma',
                             **kwargs)">
     <%call expr="longhand(name, animation_value_type=animation_value_type, vector=True,
-                          **kwargs)">
+                          simple_vector_bindings=simple_vector_bindings, **kwargs)">
         #[allow(unused_imports)]
         use smallvec::SmallVec;
 
@@ -111,16 +125,46 @@
 
         /// The definition of the computed value for ${name}.
         pub mod computed_value {
+            #[allow(unused_imports)]
+            use crate::values::animated::ToAnimatedValue;
+            #[allow(unused_imports)]
+            use crate::values::resolved::ToResolvedValue;
             pub use super::single_value::computed_value as single_value;
             pub use self::single_value::T as SingleComputedValue;
-            % if allow_empty and allow_empty != "NotInitial":
-            use std::vec::IntoIter;
-            % else:
-            use smallvec::{IntoIter, SmallVec};
+            % if not allow_empty or allow_empty == "NotInitial":
+            use smallvec::SmallVec;
             % endif
             use crate::values::computed::ComputedVecIter;
 
-            /// The generic type defining the value for this property.
+            <%
+                is_shared_list = allow_empty and allow_empty != "NotInitial" and \
+                    data.longhands_by_name[name].style_struct.inherited
+            %>
+
+            // FIXME(emilio): Add an OwnedNonEmptySlice type, and figure out
+            // something for transition-name, which is the only remaining user
+            // of NotInitial.
+            pub type UnderlyingList<T> =
+                % if allow_empty and allow_empty != "NotInitial":
+                % if data.longhands_by_name[name].style_struct.inherited:
+                    crate::ArcSlice<T>;
+                % else:
+                    crate::OwnedSlice<T>;
+                % endif
+                % else:
+                    SmallVec<[T; 1]>;
+                % endif
+
+            pub type UnderlyingOwnedList<T> =
+                % if allow_empty and allow_empty != "NotInitial":
+                    crate::OwnedSlice<T>;
+                % else:
+                    SmallVec<[T; 1]>;
+                % endif
+
+
+            /// The generic type defining the animated and resolved values for
+            /// this property.
             ///
             /// Making this type generic allows the compiler to figure out the
             /// animated value for us, instead of having to implement it
@@ -137,34 +181,115 @@
                 ToResolvedValue,
                 ToCss,
             )]
-            pub struct List<T>(
+            pub struct OwnedList<T>(
                 % if not allow_empty:
                 #[css(iterable)]
                 % else:
                 #[css(if_empty = "none", iterable)]
                 % endif
-                % if allow_empty and allow_empty != "NotInitial":
-                pub Vec<T>,
+                pub UnderlyingOwnedList<T>,
+            );
+
+            /// The computed value for this property.
+            % if not is_shared_list:
+            pub type ComputedList = OwnedList<single_value::T>;
+            pub use self::OwnedList as List;
+            % else:
+            pub use self::ComputedList as List;
+
+            % if separator == "Comma":
+            #[css(comma)]
+            % endif
+            #[derive(
+                Clone,
+                Debug,
+                MallocSizeOf,
+                PartialEq,
+                ToCss,
+            )]
+            pub struct ComputedList(
+                % if not allow_empty:
+                #[css(iterable)]
                 % else:
-                pub SmallVec<[T; 1]>,
+                #[css(if_empty = "none", iterable)]
+                % endif
+                % if is_shared_list:
+                #[ignore_malloc_size_of = "Arc"]
                 % endif
+                pub UnderlyingList<single_value::T>,
             );
 
+            type ResolvedList = OwnedList<<single_value::T as ToResolvedValue>::ResolvedValue>;
+            impl ToResolvedValue for ComputedList {
+                type ResolvedValue = ResolvedList;
+
+                fn to_resolved_value(self, context: &crate::values::resolved::Context) -> Self::ResolvedValue {
+                    OwnedList(
+                        self.0
+                            .iter()
+                            .cloned()
+                            .map(|v| v.to_resolved_value(context))
+                            .collect()
+                    )
+                }
+
+                fn from_resolved_value(resolved: Self::ResolvedValue) -> Self {
+                    % if not is_shared_list:
+                    use std::iter::FromIterator;
+                    % endif
+                    let iter =
+                        resolved.0.into_iter().map(ToResolvedValue::from_resolved_value);
+                    ComputedList(UnderlyingList::from_iter(iter))
+                }
+            }
+            % endif
+
+            % if simple_vector_bindings:
+            impl From<ComputedList> for UnderlyingList<single_value::T> {
+                #[inline]
+                fn from(l: ComputedList) -> Self {
+                    l.0
+                }
+            }
+            impl From<UnderlyingList<single_value::T>> for ComputedList {
+                #[inline]
+                fn from(l: UnderlyingList<single_value::T>) -> Self {
+                    List(l)
+                }
+            }
+            % endif
 
-            /// The computed value, effectively a list of single values.
             % if vector_animation_type:
             % if not animation_value_type:
                 Sorry, this is stupid but needed for now.
             % endif
 
             use crate::properties::animated_properties::ListAnimation;
-            use crate::values::animated::{Animate, ToAnimatedValue, ToAnimatedZero, Procedure};
+            use crate::values::animated::{Animate, ToAnimatedZero, Procedure};
             use crate::values::distance::{SquaredDistance, ComputeSquaredDistance};
 
             // FIXME(emilio): For some reason rust thinks that this alias is
             // unused, even though it's clearly used below?
             #[allow(unused)]
-            type AnimatedList = <List<single_value::T> as ToAnimatedValue>::AnimatedValue;
+            type AnimatedList = OwnedList<<single_value::T as ToAnimatedValue>::AnimatedValue>;
+
+            % if is_shared_list:
+            impl ToAnimatedValue for ComputedList {
+                type AnimatedValue = AnimatedList;
+
+                fn to_animated_value(self) -> Self::AnimatedValue {
+                    OwnedList(
+                        self.0.iter().map(|v| v.clone().to_animated_value()).collect()
+                    )
+                }
+
+                fn from_animated_value(animated: Self::AnimatedValue) -> Self {
+                    let iter =
+                        animated.0.into_iter().map(ToAnimatedValue::from_animated_value);
+                    ComputedList(UnderlyingList::from_iter(iter))
+                }
+            }
+            % endif
 
             impl ToAnimatedZero for AnimatedList {
                 fn to_animated_zero(&self) -> Result<Self, ()> { Err(()) }
@@ -176,7 +301,7 @@
                     other: &Self,
                     procedure: Procedure,
                 ) -> Result<Self, ()> {
-                    Ok(List(
+                    Ok(OwnedList(
                         self.0.animate_${vector_animation_type}(&other.0, procedure)?
                     ))
                 }
@@ -191,21 +316,10 @@
             }
             % endif
 
-            pub type T = List<single_value::T>;
+            /// The computed value, effectively a list of single values.
+            pub use self::ComputedList as T;
 
             pub type Iter<'a, 'cx, 'cx_a> = ComputedVecIter<'a, 'cx, 'cx_a, super::single_value::SpecifiedValue>;
-
-            impl IntoIterator for T {
-                type Item = single_value::T;
-                % if allow_empty and allow_empty != "NotInitial":
-                type IntoIter = IntoIter<single_value::T>;
-                % else:
-                type IntoIter = IntoIter<[single_value::T; 1]>;
-                % endif
-                fn into_iter(self) -> Self::IntoIter {
-                    self.0.into_iter()
-                }
-            }
         }
 
         /// The specified value of ${name}.
@@ -219,12 +333,12 @@
             % else:
             #[css(if_empty = "none", iterable)]
             % endif
-            pub Vec<single_value::SpecifiedValue>,
+            pub crate::OwnedSlice<single_value::SpecifiedValue>,
         );
 
         pub fn get_initial_value() -> computed_value::T {
             % if allow_empty and allow_empty != "NotInitial":
-                computed_value::List(vec![])
+                computed_value::List(Default::default())
             % else:
                 let mut v = SmallVec::new();
                 v.push(single_value::get_initial_value());
@@ -239,40 +353,47 @@
             use style_traits::Separator;
 
             % if allow_empty:
-                if input.try(|input| input.expect_ident_matching("none")).is_ok() {
-                    return Ok(SpecifiedValue(Vec::new()))
-                }
+            if input.try(|input| input.expect_ident_matching("none")).is_ok() {
+                return Ok(SpecifiedValue(Default::default()))
+            }
             % endif
 
-            style_traits::${separator}::parse(input, |parser| {
+            let v = style_traits::${separator}::parse(input, |parser| {
                 single_value::parse(context, parser)
-            }).map(SpecifiedValue)
+            })?;
+            Ok(SpecifiedValue(v.into()))
         }
 
         pub use self::single_value::SpecifiedValue as SingleSpecifiedValue;
 
+        % if not simple_vector_bindings and product == "gecko":
         impl SpecifiedValue {
-            pub fn compute_iter<'a, 'cx, 'cx_a>(
+            fn compute_iter<'a, 'cx, 'cx_a>(
                 &'a self,
                 context: &'cx Context<'cx_a>,
             ) -> computed_value::Iter<'a, 'cx, 'cx_a> {
                 computed_value::Iter::new(context, &self.0)
             }
         }
+        % endif
 
         impl ToComputedValue for SpecifiedValue {
             type ComputedValue = computed_value::T;
 
             #[inline]
             fn to_computed_value(&self, context: &Context) -> computed_value::T {
-                computed_value::List(self.compute_iter(context).collect())
+                % if not is_shared_list:
+                use std::iter::FromIterator;
+                % endif
+                computed_value::List(computed_value::UnderlyingList::from_iter(
+                    self.0.iter().map(|i| i.to_computed_value(context))
+                ))
             }
 
             #[inline]
             fn from_computed_value(computed: &computed_value::T) -> Self {
-                SpecifiedValue(computed.0.iter()
-                                    .map(ToComputedValue::from_computed_value)
-                                    .collect())
+                let iter = computed.0.iter().map(ToComputedValue::from_computed_value);
+                SpecifiedValue(iter.collect())
             }
         }
     </%call>
@@ -375,7 +496,7 @@
                     .set_writing_mode_dependency(context.builder.writing_mode);
             % endif
 
-            % if property.is_vector:
+            % if property.is_vector and not property.simple_vector_bindings and product == "gecko":
                 // In the case of a vector property we want to pass down an
                 // iterator so that this can be computed without allocation.
                 //
@@ -405,8 +526,8 @@
             context: &ParserContext,
             input: &mut Parser<'i, 't>,
         ) -> Result<PropertyDeclaration, ParseError<'i>> {
-            % if property.allow_quirks:
-                parse_quirky(context, input, specified::AllowQuirks::Yes)
+            % if property.allow_quirks != "No":
+                parse_quirky(context, input, specified::AllowQuirks::${property.allow_quirks})
             % else:
                 parse(context, input)
             % endif
@@ -868,7 +989,7 @@
 </%def>
 
 <%def name="four_sides_shorthand(name, sub_property_pattern, parser_function,
-                                 needs_context=True, allow_quirks=False, **kwargs)">
+                                 needs_context=True, allow_quirks='No', **kwargs)">
     <% sub_properties=' '.join(sub_property_pattern % side for side in PHYSICAL_SIDES) %>
     <%call expr="self.shorthand(name, sub_properties=sub_properties, **kwargs)">
         #[allow(unused_imports)]
@@ -881,8 +1002,8 @@
             input: &mut Parser<'i, 't>,
         ) -> Result<Longhands, ParseError<'i>> {
             let rect = Rect::parse_with(context, input, |_c, i| {
-            % if allow_quirks:
-                ${parser_function}_quirky(_c, i, specified::AllowQuirks::Yes)
+            % if allow_quirks != "No":
+                ${parser_function}_quirky(_c, i, specified::AllowQuirks::${allow_quirks})
             % elif needs_context:
                 ${parser_function}(_c, i)
             % else:
diff --git a/components/style/properties/helpers/animated_properties.mako.rs b/components/style/properties/helpers/animated_properties.mako.rs
index aa2d0247e82..d3b3ecd11e4 100644
--- a/components/style/properties/helpers/animated_properties.mako.rs
+++ b/components/style/properties/helpers/animated_properties.mako.rs
@@ -9,9 +9,7 @@
     from itertools import groupby
 %>
 
-#[cfg(feature = "gecko")] use crate::gecko_bindings::structs::RawServoAnimationValueMap;
 #[cfg(feature = "gecko")] use crate::gecko_bindings::structs::nsCSSPropertyID;
-#[cfg(feature = "gecko")] use crate::gecko_bindings::sugar::ownership::{HasFFI, HasSimpleFFI};
 use itertools::{EitherOrBoth, Itertools};
 use crate::properties::{CSSWideKeyword, PropertyDeclaration};
 use crate::properties::longhands;
@@ -190,13 +188,6 @@ impl AnimatedProperty {
 /// composed for each TransitionProperty.
 pub type AnimationValueMap = FxHashMap<LonghandId, AnimationValue>;
 
-#[cfg(feature = "gecko")]
-unsafe impl HasFFI for AnimationValueMap {
-    type FFIType = RawServoAnimationValueMap;
-}
-#[cfg(feature = "gecko")]
-unsafe impl HasSimpleFFI for AnimationValueMap {}
-
 /// An enum to represent a single computed value belonging to an animated
 /// property in order to be interpolated with another one. When interpolating,
 /// both values need to belong to the same property.
@@ -773,6 +764,7 @@ macro_rules! animated_list_impl {
     }
 }
 
+animated_list_impl!(<T> for crate::OwnedSlice<T>);
 animated_list_impl!(<T> for SmallVec<[T; 1]>);
 animated_list_impl!(<T> for Vec<T>);
 
diff --git a/components/style/properties/longhands/background.mako.rs b/components/style/properties/longhands/background.mako.rs
index 42344a18cb9..9c66e4676f9 100644
--- a/components/style/properties/longhands/background.mako.rs
+++ b/components/style/properties/longhands/background.mako.rs
@@ -14,7 +14,7 @@ ${helpers.predefined_type(
     spec="https://drafts.csswg.org/css-backgrounds/#background-color",
     animation_value_type="AnimatedColor",
     ignored_when_colors_disabled=True,
-    allow_quirks=True,
+    allow_quirks="Yes",
     flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER \
            CAN_ANIMATE_ON_COMPOSITOR",
 )}
diff --git a/components/style/properties/longhands/border.mako.rs b/components/style/properties/longhands/border.mako.rs
index 13a7f237350..7909372be17 100644
--- a/components/style/properties/longhands/border.mako.rs
+++ b/components/style/properties/longhands/border.mako.rs
@@ -28,7 +28,7 @@
         animation_value_type="AnimatedColor",
         logical=is_logical,
         logical_group="border-color",
-        allow_quirks=not is_logical,
+        allow_quirks="No" if is_logical else "Yes",
         flags="APPLIES_TO_FIRST_LETTER",
         ignored_when_colors_disabled=True,
     )}
@@ -56,7 +56,7 @@
         logical=is_logical,
         logical_group="border-width",
         flags="APPLIES_TO_FIRST_LETTER GETCS_NEEDS_LAYOUT_FLUSH",
-        allow_quirks=not is_logical,
+        allow_quirks="No" if is_logical else "Yes",
         servo_restyle_damage="reflow rebuild_and_reflow_inline"
     )}
 % endfor
@@ -159,60 +159,3 @@ ${helpers.predefined_type(
     flags="APPLIES_TO_FIRST_LETTER",
     boxed=True,
 )}
-
-// FIXME(emilio): Why does this live here? ;_;
-#[cfg(feature = "gecko")]
-impl crate::values::computed::BorderImageWidth {
-    pub fn to_gecko_rect(&self, sides: &mut crate::gecko_bindings::structs::nsStyleSides) {
-        use crate::gecko_bindings::sugar::ns_style_coord::{CoordDataMut, CoordDataValue};
-        use crate::gecko::values::GeckoStyleCoordConvertible;
-        use crate::values::generics::border::BorderImageSideWidth;
-
-        % for i in range(0, 4):
-        match self.${i} {
-            BorderImageSideWidth::Auto => {
-                sides.data_at_mut(${i}).set_value(CoordDataValue::Auto)
-            },
-            BorderImageSideWidth::Length(l) => {
-                l.to_gecko_style_coord(&mut sides.data_at_mut(${i}))
-            },
-            BorderImageSideWidth::Number(n) => {
-                sides.data_at_mut(${i}).set_value(CoordDataValue::Factor(n.0))
-            },
-        }
-        % endfor
-    }
-
-    pub fn from_gecko_rect(
-        sides: &crate::gecko_bindings::structs::nsStyleSides,
-    ) -> Option<crate::values::computed::BorderImageWidth> {
-        use crate::gecko_bindings::structs::nsStyleUnit::{eStyleUnit_Factor, eStyleUnit_Auto};
-        use crate::gecko_bindings::sugar::ns_style_coord::CoordData;
-        use crate::gecko::values::GeckoStyleCoordConvertible;
-        use crate::values::computed::{LengthPercentage, Number};
-        use crate::values::generics::border::BorderImageSideWidth;
-        use crate::values::generics::NonNegative;
-
-        Some(
-            crate::values::computed::BorderImageWidth::new(
-                % for i in range(0, 4):
-                match sides.data_at(${i}).unit() {
-                    eStyleUnit_Auto => {
-                        BorderImageSideWidth::Auto
-                    },
-                    eStyleUnit_Factor => {
-                        BorderImageSideWidth::Number(
-                            NonNegative(Number::from_gecko_style_coord(&sides.data_at(${i}))
-                                .expect("sides[${i}] could not convert to Number")))
-                    },
-                    _ => {
-                        BorderImageSideWidth::Length(
-                            NonNegative(LengthPercentage::from_gecko_style_coord(&sides.data_at(${i}))
-                                .expect("sides[${i}] could not convert to LengthPercentage")))
-                    },
-                },
-                % endfor
-            )
-        )
-    }
-}
diff --git a/components/style/properties/longhands/box.mako.rs b/components/style/properties/longhands/box.mako.rs
index 6d754964ecc..da9e5b2e767 100644
--- a/components/style/properties/longhands/box.mako.rs
+++ b/components/style/properties/longhands/box.mako.rs
@@ -309,41 +309,6 @@ ${helpers.predefined_type(
     allowed_in_keyframe_block=False,
 )}
 
-% for axis in ["x", "y"]:
-    ${helpers.predefined_type(
-        "scroll-snap-points-" + axis,
-        "ScrollSnapPoint",
-        "computed::ScrollSnapPoint::none()",
-        animation_value_type="discrete",
-        gecko_pref="layout.css.scroll-snap.enabled",
-        products="gecko",
-        spec="Nonstandard (https://www.w3.org/TR/2015/WD-css-snappoints-1-20150326/#scroll-snap-points)",
-    )}
-% endfor
-
-${helpers.predefined_type(
-    "scroll-snap-destination",
-    "Position",
-    "computed::Position::zero()",
-    products="gecko",
-    gecko_pref="layout.css.scroll-snap.enabled",
-    boxed=True,
-    spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/scroll-snap-destination)",
-    animation_value_type="discrete",
-)}
-
-${helpers.predefined_type(
-    "scroll-snap-coordinate",
-    "Position",
-    "computed::Position::zero()",
-    vector=True,
-    allow_empty=True,
-    products="gecko",
-    gecko_pref="layout.css.scroll-snap.enabled",
-    spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/scroll-snap-destination)",
-    animation_value_type="discrete",
-)}
-
 <% transform_extra_prefixes = "moz:layout.css.prefixes.transforms webkit" %>
 
 ${helpers.predefined_type(
@@ -352,7 +317,6 @@ ${helpers.predefined_type(
     "generics::transform::Transform::none()",
     extra_prefixes=transform_extra_prefixes,
     animation_value_type="ComputedValue",
-    gecko_ffi_name="mSpecifiedTransform",
     flags="CREATES_STACKING_CONTEXT FIXPOS_CB \
            GETCS_NEEDS_LAYOUT_FLUSH CAN_ANIMATE_ON_COMPOSITOR",
     spec="https://drafts.csswg.org/css-transforms/#propdef-transform",
@@ -405,6 +369,31 @@ ${helpers.predefined_type(
     gecko_pref="layout.css.motion-path.enabled",
     flags="CREATES_STACKING_CONTEXT FIXPOS_CB",
     spec="https://drafts.fxtf.org/motion-1/#offset-path-property",
+    servo_restyle_damage="reflow_out_of_flow"
+)}
+
+// Motion Path Module Level 1
+${helpers.predefined_type(
+    "offset-distance",
+    "LengthPercentage",
+    "computed::LengthPercentage::zero()",
+    products="gecko",
+    animation_value_type="ComputedValue",
+    gecko_pref="layout.css.motion-path.enabled",
+    spec="https://drafts.fxtf.org/motion-1/#offset-distance-property",
+    servo_restyle_damage="reflow_out_of_flow"
+)}
+
+// Motion Path Module Level 1
+${helpers.predefined_type(
+    "offset-rotate",
+    "OffsetRotate",
+    "computed::OffsetRotate::auto()",
+    products="gecko",
+    animation_value_type="none",
+    gecko_pref="layout.css.motion-path.enabled",
+    spec="https://drafts.fxtf.org/motion-1/#offset-rotate-property",
+    servo_restyle_damage="reflow_out_of_flow"
 )}
 
 // CSSOM View Module
diff --git a/components/style/properties/longhands/color.mako.rs b/components/style/properties/longhands/color.mako.rs
index b367f2bbd86..a83787dd48e 100644
--- a/components/style/properties/longhands/color.mako.rs
+++ b/components/style/properties/longhands/color.mako.rs
@@ -35,6 +35,7 @@ pub mod system_colors {
                            -moz-eventreerow -moz-field -moz-fieldtext -moz-dialog -moz-dialogtext
                            -moz-dragtargetzone -moz-gtk-info-bar-text -moz-html-cellhighlight
                            -moz-html-cellhighlighttext -moz-mac-buttonactivetext
+                           -moz-gtk-buttonactivetext
                            -moz-mac-chrome-active -moz-mac-chrome-inactive
                            -moz-mac-defaultbuttontext -moz-mac-focusring -moz-mac-menuselect
                            -moz-mac-menushadow -moz-mac-menutextdisable -moz-mac-menutextselect
diff --git a/components/style/properties/longhands/effects.mako.rs b/components/style/properties/longhands/effects.mako.rs
index 0b3f96f0dde..9bb8adda32e 100644
--- a/components/style/properties/longhands/effects.mako.rs
+++ b/components/style/properties/longhands/effects.mako.rs
@@ -23,6 +23,7 @@ ${helpers.predefined_type(
     "BoxShadow",
     None,
     vector=True,
+    simple_vector_bindings=True,
     animation_value_type="AnimatedBoxShadowList",
     vector_animation_type="with_zero",
     extra_prefixes="webkit",
@@ -37,7 +38,7 @@ ${helpers.predefined_type(
     "computed::ClipRectOrAuto::auto()",
     animation_value_type="ComputedValue",
     boxed=True,
-    allow_quirks=True,
+    allow_quirks="Yes",
     spec="https://drafts.fxtf.org/css-masking/#clip-property",
 )}
 
diff --git a/components/style/properties/longhands/font.mako.rs b/components/style/properties/longhands/font.mako.rs
index c1d3d8fcc6c..8d84ef34cb3 100644
--- a/components/style/properties/longhands/font.mako.rs
+++ b/components/style/properties/longhands/font.mako.rs
@@ -64,7 +64,7 @@ ${helpers.predefined_type(
     initial_value="computed::FontSize::medium()",
     initial_specified_value="specified::FontSize::medium()",
     animation_value_type="NonNegativeLength",
-    allow_quirks=True,
+    allow_quirks="Yes",
     flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
     spec="https://drafts.csswg.org/css-fonts/#propdef-font-size",
     servo_restyle_damage="rebuild_and_reflow",
diff --git a/components/style/properties/longhands/inherited_svg.mako.rs b/components/style/properties/longhands/inherited_svg.mako.rs
index 2bbdc2794c2..c3e16ee475f 100644
--- a/components/style/properties/longhands/inherited_svg.mako.rs
+++ b/components/style/properties/longhands/inherited_svg.mako.rs
@@ -194,11 +194,8 @@ ${helpers.predefined_type(
 ${helpers.predefined_type(
     "-moz-context-properties",
     "MozContextProperties",
-    initial_value=None,
-    vector=True,
-    need_index=True,
-    animation_value_type="none",
+    "computed::MozContextProperties::default()",
     products="gecko",
+    animation_value_type="none",
     spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/-moz-context-properties)",
-    allow_empty=True,
 )}
diff --git a/components/style/properties/longhands/inherited_text.mako.rs b/components/style/properties/longhands/inherited_text.mako.rs
index cdd7df93256..e8f56cf2cde 100644
--- a/components/style/properties/longhands/inherited_text.mako.rs
+++ b/components/style/properties/longhands/inherited_text.mako.rs
@@ -56,7 +56,7 @@ ${helpers.predefined_type(
     "computed::LengthPercentage::zero()",
     animation_value_type="ComputedValue",
     spec="https://drafts.csswg.org/css-text/#propdef-text-indent",
-    allow_quirks=True,
+    allow_quirks="Yes",
     servo_restyle_damage = "reflow",
 )}
 
@@ -218,6 +218,7 @@ ${helpers.predefined_type(
     vector_animation_type="with_zero",
     animation_value_type="AnimatedTextShadowList",
     ignored_when_colors_disabled=True,
+    simple_vector_bindings=True,
     flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
     spec="https://drafts.csswg.org/css-text-decor-3/#text-shadow-property",
 )}
@@ -263,6 +264,16 @@ ${helpers.predefined_type(
     spec="https://drafts.csswg.org/css-text-3/#tab-size-property",
 )}
 
+${helpers.predefined_type(
+    "line-break",
+    "LineBreak",
+    "computed::LineBreak::Auto",
+    products="gecko",
+    animation_value_type="discrete",
+    spec="https://drafts.csswg.org/css-text-3/#line-break-property",
+    needs_context=False,
+)}
+
 // CSS Compatibility
 // https://compat.spec.whatwg.org
 ${helpers.predefined_type(
diff --git a/components/style/properties/longhands/margin.mako.rs b/components/style/properties/longhands/margin.mako.rs
index d2a3be11d1d..c3289c34b7c 100644
--- a/components/style/properties/longhands/margin.mako.rs
+++ b/components/style/properties/longhands/margin.mako.rs
@@ -17,7 +17,7 @@
         "LengthPercentageOrAuto",
         "computed::LengthPercentageOrAuto::zero()",
         alias=maybe_moz_logical_alias(product, side, "-moz-margin-%s"),
-        allow_quirks=not side[1],
+        allow_quirks="No" if side[1] else "Yes",
         animation_value_type="ComputedValue",
         logical=side[1],
         logical_group="margin",
diff --git a/components/style/properties/longhands/padding.mako.rs b/components/style/properties/longhands/padding.mako.rs
index a1262aee0fc..6142bbf901e 100644
--- a/components/style/properties/longhands/padding.mako.rs
+++ b/components/style/properties/longhands/padding.mako.rs
@@ -24,7 +24,7 @@
         logical_group="padding",
         spec=spec,
         flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_PLACEHOLDER GETCS_NEEDS_LAYOUT_FLUSH",
-        allow_quirks=not side[1],
+        allow_quirks="No" if side[1] else "Yes",
         servo_restyle_damage="reflow rebuild_and_reflow_inline"
     )}
 % endfor
diff --git a/components/style/properties/longhands/position.mako.rs b/components/style/properties/longhands/position.mako.rs
index 096349f4b1c..34216385fed 100644
--- a/components/style/properties/longhands/position.mako.rs
+++ b/components/style/properties/longhands/position.mako.rs
@@ -17,7 +17,7 @@
         spec="https://www.w3.org/TR/CSS2/visuren.html#propdef-%s" % side,
         flags="GETCS_NEEDS_LAYOUT_FLUSH",
         animation_value_type="ComputedValue",
-        allow_quirks=True,
+        allow_quirks="Yes",
         servo_restyle_damage="reflow_out_of_flow",
         logical_group="inset",
     )}
@@ -253,7 +253,7 @@ ${helpers.predefined_type(
         "computed::Size::auto()",
         logical=logical,
         logical_group="size",
-        allow_quirks=not logical,
+        allow_quirks="No" if logical else "Yes",
         spec=spec % size,
         animation_value_type="Size",
         flags="GETCS_NEEDS_LAYOUT_FLUSH",
@@ -266,7 +266,7 @@ ${helpers.predefined_type(
         "computed::Size::auto()",
         logical=logical,
         logical_group="min-size",
-        allow_quirks=not logical,
+        allow_quirks="No" if logical else "Yes",
         spec=spec % size,
         animation_value_type="Size",
         servo_restyle_damage="reflow",
@@ -277,7 +277,7 @@ ${helpers.predefined_type(
         "computed::MaxSize::none()",
         logical=logical,
         logical_group="max-size",
-        allow_quirks=not logical,
+        allow_quirks="No" if logical else "Yes",
         spec=spec % size,
         animation_value_type="MaxSize",
         servo_restyle_damage="reflow",
diff --git a/components/style/properties/longhands/svg.mako.rs b/components/style/properties/longhands/svg.mako.rs
index 3e4d207397a..8e93d03dbb1 100644
--- a/components/style/properties/longhands/svg.mako.rs
+++ b/components/style/properties/longhands/svg.mako.rs
@@ -191,3 +191,66 @@ ${helpers.predefined_type(
     animation_value_type="discrete",
     flags="CREATES_STACKING_CONTEXT",
 )}
+
+${helpers.predefined_type(
+    "x",
+    "LengthPercentage",
+    "computed::LengthPercentage::zero()",
+    products="gecko",
+    animation_value_type="ComputedValue",
+    spec="https://svgwg.org/svg2-draft/geometry.html#X",
+)}
+
+${helpers.predefined_type(
+    "y",
+    "LengthPercentage",
+    "computed::LengthPercentage::zero()",
+    products="gecko",
+    animation_value_type="ComputedValue",
+    spec="https://svgwg.org/svg2-draft/geometry.html#Y",
+)}
+
+${helpers.predefined_type(
+    "cx",
+    "LengthPercentage",
+    "computed::LengthPercentage::zero()",
+    products="gecko",
+    animation_value_type="ComputedValue",
+    spec="https://svgwg.org/svg2-draft/geometry.html#CX",
+)}
+
+${helpers.predefined_type(
+    "cy",
+    "LengthPercentage",
+    "computed::LengthPercentage::zero()",
+    products="gecko",
+    animation_value_type="ComputedValue",
+    spec="https://svgwg.org/svg2-draft/geometry.html#CY",
+)}
+
+${helpers.predefined_type(
+    "rx",
+    "NonNegativeLengthPercentageOrAuto",
+    "computed::NonNegativeLengthPercentageOrAuto::auto()",
+    products="gecko",
+    animation_value_type="LengthPercentageOrAuto",
+    spec="https://svgwg.org/svg2-draft/geometry.html#RX",
+)}
+
+${helpers.predefined_type(
+    "ry",
+    "NonNegativeLengthPercentageOrAuto",
+    "computed::NonNegativeLengthPercentageOrAuto::auto()",
+    products="gecko",
+    animation_value_type="LengthPercentageOrAuto",
+    spec="https://svgwg.org/svg2-draft/geometry.html#RY",
+)}
+
+${helpers.predefined_type(
+    "r",
+    "NonNegativeLengthPercentage",
+    "computed::NonNegativeLengthPercentage::zero()",
+    products="gecko",
+    animation_value_type="LengthPercentage",
+    spec="https://svgwg.org/svg2-draft/geometry.html#R",
+)}
diff --git a/components/style/properties/longhands/ui.mako.rs b/components/style/properties/longhands/ui.mako.rs
index c54582e2584..5c51569089c 100644
--- a/components/style/properties/longhands/ui.mako.rs
+++ b/components/style/properties/longhands/ui.mako.rs
@@ -32,12 +32,11 @@ ${helpers.single_keyword(
 )}
 
 ${helpers.predefined_type(
-    "-moz-user-select",
+    "user-select",
     "UserSelect",
     "computed::UserSelect::Auto",
     products="gecko",
-    gecko_ffi_name="mUserSelect",
-    alias="-webkit-user-select",
+    extra_prefixes="moz webkit",
     animation_value_type="discrete",
     needs_context=False,
     spec="https://drafts.csswg.org/css-ui-4/#propdef-user-select",
@@ -81,7 +80,6 @@ ${helpers.predefined_type(
     "Transform",
     "generics::transform::Transform::none()",
     products="gecko",
-    gecko_ffi_name="mSpecifiedWindowTransform",
     flags="GETCS_NEEDS_LAYOUT_FLUSH",
     animation_value_type="ComputedValue",
     spec="None (Nonstandard internal property)",
diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index a9fa35ba444..520b4a32b51 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -2337,6 +2337,14 @@ impl SourcePropertyDeclaration {
         }
     }
 
+    /// Create one with a single PropertyDeclaration.
+    #[inline]
+    pub fn with_one(decl: PropertyDeclaration) -> Self {
+        let mut result = Self::new();
+        result.declarations.push(decl);
+        result
+    }
+
     /// Similar to Vec::drain: leaves this empty when the return value is dropped.
     pub fn drain(&mut self) -> SourcePropertyDeclarationDrain {
         SourcePropertyDeclarationDrain {
@@ -2474,20 +2482,7 @@ pub mod style_structs {
                 % if longhand.logical:
                     ${helpers.logical_setter(name=longhand.name)}
                 % else:
-                    % if longhand.is_vector:
-                        /// Set ${longhand.name}.
-                        #[allow(non_snake_case)]
-                        #[inline]
-                        pub fn set_${longhand.ident}<I>(&mut self, v: I)
-                        where
-                            I: IntoIterator<Item = longhands::${longhand.ident}
-                                                              ::computed_value::single_value::T>,
-                            I::IntoIter: ExactSizeIterator
-                        {
-                            self.${longhand.ident} = longhands::${longhand.ident}::computed_value
-                                                              ::List(v.into_iter().collect());
-                        }
-                    % elif longhand.ident == "display":
+                    % if longhand.ident == "display":
                         /// Set `display`.
                         ///
                         /// We need to keep track of the original display for hypothetical boxes,
@@ -3101,7 +3096,7 @@ impl ComputedValuesInner {
     pub fn transform_requires_layer(&self) -> bool {
         use crate::values::generics::transform::TransformOperation;
         // Check if the transform matrix is 2D or 3D
-        for transform in &self.get_box().transform.0 {
+        for transform in &*self.get_box().transform.0 {
             match *transform {
                 TransformOperation::Perspective(..) => {
                     return true;
@@ -3444,7 +3439,7 @@ impl<'a> StyleBuilder<'a> {
     }
     % endif
 
-    % if not property.is_vector:
+    % if not property.is_vector or property.simple_vector_bindings or product != "gecko":
     /// Set the `${property.ident}` to the computed value `value`.
     #[allow(non_snake_case)]
     pub fn set_${property.ident}(
diff --git a/components/style/properties/shorthands/background.mako.rs b/components/style/properties/shorthands/background.mako.rs
index c73009ab2ba..af98342bfe6 100644
--- a/components/style/properties/shorthands/background.mako.rs
+++ b/components/style/properties/shorthands/background.mako.rs
@@ -40,11 +40,11 @@
         let mut background_color = None;
 
         % for name in "image position_x position_y repeat size attachment origin clip".split():
-            // Vec grows from 0 to 4 by default on first push().  So allocate
-            // with capacity 1, so in the common case of only one item we don't
-            // way overallocate.  Note that we always push at least one item if
-            // parsing succeeds.
-            let mut background_${name} = background_${name}::SpecifiedValue(Vec::with_capacity(1));
+        // Vec grows from 0 to 4 by default on first push().  So allocate with
+        // capacity 1, so in the common case of only one item we don't way
+        // overallocate, then shrink.  Note that we always push at least one
+        // item if parsing succeeds.
+        let mut background_${name} = Vec::with_capacity(1);
         % endfor
         input.parse_comma_separated(|input| {
             // background-color can only be in the last element, so if it
@@ -99,17 +99,17 @@
             any = any || background_color.is_some();
             if any {
                 if let Some(position) = position {
-                    background_position_x.0.push(position.horizontal);
-                    background_position_y.0.push(position.vertical);
+                    background_position_x.push(position.horizontal);
+                    background_position_y.push(position.vertical);
                 } else {
-                    background_position_x.0.push(PositionComponent::zero());
-                    background_position_y.0.push(PositionComponent::zero());
+                    background_position_x.push(PositionComponent::zero());
+                    background_position_y.push(PositionComponent::zero());
                 }
                 % for name in "image repeat size attachment origin clip".split():
                     if let Some(bg_${name}) = ${name} {
-                        background_${name}.0.push(bg_${name});
+                        background_${name}.push(bg_${name});
                     } else {
-                        background_${name}.0.push(background_${name}::single_value
+                        background_${name}.push(background_${name}::single_value
                                                                     ::get_initial_specified_value());
                     }
                 % endfor
@@ -121,14 +121,9 @@
 
         Ok(expanded! {
              background_color: background_color.unwrap_or(Color::transparent()),
-             background_image: background_image,
-             background_position_x: background_position_x,
-             background_position_y: background_position_y,
-             background_repeat: background_repeat,
-             background_attachment: background_attachment,
-             background_size: background_size,
-             background_origin: background_origin,
-             background_clip: background_clip,
+             % for name in "image position_x position_y repeat size attachment origin clip".split():
+             background_${name}: background_${name}::SpecifiedValue(background_${name}.into()),
+             % endfor
          })
     }
 
@@ -209,16 +204,16 @@
     ) -> Result<Longhands, ParseError<'i>> {
         // Vec grows from 0 to 4 by default on first push().  So allocate with
         // capacity 1, so in the common case of only one item we don't way
-        // overallocate.  Note that we always push at least one item if parsing
-        // succeeds.
-        let mut position_x = background_position_x::SpecifiedValue(Vec::with_capacity(1));
-        let mut position_y = background_position_y::SpecifiedValue(Vec::with_capacity(1));
+        // overallocate, then shrink.  Note that we always push at least one
+        // item if parsing succeeds.
+        let mut position_x = Vec::with_capacity(1);
+        let mut position_y = Vec::with_capacity(1);
         let mut any = false;
 
         input.parse_comma_separated(|input| {
             let value = Position::parse_quirky(context, input, AllowQuirks::Yes)?;
-            position_x.0.push(value.horizontal);
-            position_y.0.push(value.vertical);
+            position_x.push(value.horizontal);
+            position_y.push(value.vertical);
             any = true;
             Ok(())
         })?;
@@ -227,8 +222,8 @@
         }
 
         Ok(expanded! {
-            background_position_x: position_x,
-            background_position_y: position_y,
+            background_position_x: background_position_x::SpecifiedValue(position_x.into()),
+            background_position_y: background_position_y::SpecifiedValue(position_y.into()),
         })
     }
 
diff --git a/components/style/properties/shorthands/border.mako.rs b/components/style/properties/shorthands/border.mako.rs
index cd472068793..1f8df0df6a1 100644
--- a/components/style/properties/shorthands/border.mako.rs
+++ b/components/style/properties/shorthands/border.mako.rs
@@ -7,7 +7,7 @@
 
 ${helpers.four_sides_shorthand("border-color", "border-%s-color", "specified::Color::parse",
                                spec="https://drafts.csswg.org/css-backgrounds/#border-color",
-                               allow_quirks=True)}
+                               allow_quirks="Yes")}
 
 ${helpers.four_sides_shorthand(
     "border-style",
diff --git a/components/style/properties/shorthands/box.mako.rs b/components/style/properties/shorthands/box.mako.rs
index 5c03dba8529..e69593f1cc1 100644
--- a/components/style/properties/shorthands/box.mako.rs
+++ b/components/style/properties/shorthands/box.mako.rs
@@ -137,7 +137,7 @@ macro_rules! try_parse_one {
 
         Ok(expanded! {
             % for prop in "property duration timing_function delay".split():
-            transition_${prop}: transition_${prop}::SpecifiedValue(${prop}s),
+            transition_${prop}: transition_${prop}::SpecifiedValue(${prop}s.into()),
             % endfor
         })
     }
@@ -266,7 +266,7 @@ macro_rules! try_parse_one {
 
         Ok(expanded! {
             % for prop in props:
-            animation_${prop}: animation_${prop}::SpecifiedValue(${prop}s),
+            animation_${prop}: animation_${prop}::SpecifiedValue(${prop}s.into()),
             % endfor
         })
     }
diff --git a/components/style/properties/shorthands/margin.mako.rs b/components/style/properties/shorthands/margin.mako.rs
index fd3124a6ae1..9b996abbe86 100644
--- a/components/style/properties/shorthands/margin.mako.rs
+++ b/components/style/properties/shorthands/margin.mako.rs
@@ -10,7 +10,7 @@ ${helpers.four_sides_shorthand(
     "specified::LengthPercentageOrAuto::parse",
     spec="https://drafts.csswg.org/css-box/#propdef-margin",
     allowed_in_page_rule=True,
-    allow_quirks=True,
+    allow_quirks="Yes",
 )}
 
 ${helpers.two_properties_shorthand(
diff --git a/components/style/properties/shorthands/padding.mako.rs b/components/style/properties/shorthands/padding.mako.rs
index a4e013caabc..8d50c3b9e38 100644
--- a/components/style/properties/shorthands/padding.mako.rs
+++ b/components/style/properties/shorthands/padding.mako.rs
@@ -9,7 +9,7 @@ ${helpers.four_sides_shorthand(
     "padding-%s",
     "specified::NonNegativeLengthPercentage::parse",
     spec="https://drafts.csswg.org/css-box-3/#propdef-padding",
-    allow_quirks=True,
+    allow_quirks="Yes",
 )}
 
 ${helpers.two_properties_shorthand(
diff --git a/components/style/properties/shorthands/position.mako.rs b/components/style/properties/shorthands/position.mako.rs
index 6fdbe1235cf..63298b86ba1 100644
--- a/components/style/properties/shorthands/position.mako.rs
+++ b/components/style/properties/shorthands/position.mako.rs
@@ -768,7 +768,7 @@ ${helpers.four_sides_shorthand(
     "%s",
     "specified::LengthPercentageOrAuto::parse",
     spec="https://drafts.csswg.org/css-logical/#propdef-inset",
-    allow_quirks=False,
+    allow_quirks="No",
 )}
 
 ${helpers.two_properties_shorthand(
diff --git a/components/style/properties/shorthands/svg.mako.rs b/components/style/properties/shorthands/svg.mako.rs
index f6941c4e7f8..0acaff426cf 100644
--- a/components/style/properties/shorthands/svg.mako.rs
+++ b/components/style/properties/shorthands/svg.mako.rs
@@ -42,11 +42,11 @@
         input: &mut Parser<'i, 't>,
     ) -> Result<Longhands, ParseError<'i>> {
         % for name in "image mode position_x position_y size repeat origin clip composite".split():
-            // Vec grows from 0 to 4 by default on first push().  So allocate
-            // with capacity 1, so in the common case of only one item we don't
-            // way overallocate.  Note that we always push at least one item if
-            // parsing succeeds.
-            let mut mask_${name} = mask_${name}::SpecifiedValue(Vec::with_capacity(1));
+        // Vec grows from 0 to 4 by default on first push().  So allocate with
+        // capacity 1, so in the common case of only one item we don't way
+        // overallocate, then shrink.  Note that we always push at least one
+        // item if parsing succeeds.
+        let mut mask_${name} = Vec::with_capacity(1);
         % endfor
 
         input.parse_comma_separated(|input| {
@@ -96,17 +96,17 @@
             % endfor
             if any {
                 if let Some(position) = position {
-                    mask_position_x.0.push(position.horizontal);
-                    mask_position_y.0.push(position.vertical);
+                    mask_position_x.push(position.horizontal);
+                    mask_position_y.push(position.vertical);
                 } else {
-                    mask_position_x.0.push(PositionComponent::zero());
-                    mask_position_y.0.push(PositionComponent::zero());
+                    mask_position_x.push(PositionComponent::zero());
+                    mask_position_y.push(PositionComponent::zero());
                 }
                 % for name in "image mode size repeat origin clip composite".split():
                     if let Some(m_${name}) = ${name} {
-                        mask_${name}.0.push(m_${name});
+                        mask_${name}.push(m_${name});
                     } else {
-                        mask_${name}.0.push(mask_${name}::single_value
+                        mask_${name}.push(mask_${name}::single_value
                                                         ::get_initial_specified_value());
                     }
                 % endfor
@@ -118,7 +118,7 @@
 
         Ok(expanded! {
             % for name in "image mode position_x position_y size repeat origin clip composite".split():
-                mask_${name}: mask_${name},
+                mask_${name}: mask_${name}::SpecifiedValue(mask_${name}.into()),
             % endfor
          })
     }
@@ -209,16 +209,16 @@
     ) -> Result<Longhands, ParseError<'i>> {
         // Vec grows from 0 to 4 by default on first push().  So allocate with
         // capacity 1, so in the common case of only one item we don't way
-        // overallocate.  Note that we always push at least one item if parsing
-        // succeeds.
-        let mut position_x = mask_position_x::SpecifiedValue(Vec::with_capacity(1));
-        let mut position_y = mask_position_y::SpecifiedValue(Vec::with_capacity(1));
+        // overallocate, then shrink.  Note that we always push at least one
+        // item if parsing succeeds.
+        let mut position_x = Vec::with_capacity(1);
+        let mut position_y = Vec::with_capacity(1);
         let mut any = false;
 
         input.parse_comma_separated(|input| {
             let value = Position::parse(context, input)?;
-            position_x.0.push(value.horizontal);
-            position_y.0.push(value.vertical);
+            position_x.push(value.horizontal);
+            position_y.push(value.vertical);
             any = true;
             Ok(())
         })?;
@@ -227,9 +227,10 @@
             return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
         }
 
+
         Ok(expanded! {
-            mask_position_x: position_x,
-            mask_position_y: position_y,
+            mask_position_x: mask_position_x::SpecifiedValue(position_x.into()),
+            mask_position_y: mask_position_y::SpecifiedValue(position_y.into()),
         })
     }
 
diff --git a/components/style/rule_collector.rs b/components/style/rule_collector.rs
index e87a86c5e47..360b8101ef1 100644
--- a/components/style/rule_collector.rs
+++ b/components/style/rule_collector.rs
@@ -13,7 +13,7 @@ use crate::selector_parser::PseudoElement;
 use crate::shared_lock::Locked;
 use crate::stylesheets::Origin;
 use crate::stylist::{AuthorStylesEnabled, Rule, RuleInclusion, Stylist};
-use selectors::matching::{ElementSelectorFlags, MatchingContext};
+use selectors::matching::{ElementSelectorFlags, MatchingContext, MatchingMode};
 use servo_arc::ArcBorrow;
 use smallvec::SmallVec;
 
@@ -97,8 +97,15 @@ where
         context: &'a mut MatchingContext<'b, E::Impl>,
         flags_setter: &'a mut F,
     ) -> Self {
-        let rule_hash_target = element.rule_hash_target();
-        let matches_user_and_author_rules = element.matches_user_and_author_rules();
+        // When we're matching with matching_mode =
+        // `ForStatelessPseudoeElement`, the "target" for the rule hash is the
+        // element itself, since it's what's generating the pseudo-element.
+        let rule_hash_target = match context.matching_mode() {
+            MatchingMode::ForStatelessPseudoElement => element,
+            MatchingMode::Normal => element.rule_hash_target(),
+        };
+
+        let matches_user_and_author_rules = rule_hash_target.matches_user_and_author_rules();
 
         // Gecko definitely has pseudo-elements with style attributes, like
         // ::-moz-color-swatch.
@@ -120,8 +127,8 @@ where
             context,
             flags_setter,
             rules,
-            matches_user_and_author_rules,
             shadow_cascade_order: 0,
+            matches_user_and_author_rules,
             matches_document_author_rules: matches_user_and_author_rules,
         }
     }
diff --git a/components/style/style_adjuster.rs b/components/style/style_adjuster.rs
index 63af60e16ab..21b6fbd60ca 100644
--- a/components/style/style_adjuster.rs
+++ b/components/style/style_adjuster.rs
@@ -734,10 +734,7 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
         E: TElement,
     {
         if cfg!(debug_assertions) {
-            if element
-                .and_then(|e| e.implemented_pseudo_element())
-                .is_some()
-            {
+            if element.map_or(false, |e| e.is_pseudo_element()) {
                 // It'd be nice to assert `self.style.pseudo == Some(&pseudo)`,
                 // but we do resolve ::-moz-list pseudos on ::before / ::after
                 // content, sigh.
diff --git a/components/style/style_resolver.rs b/components/style/style_resolver.rs
index 11c81283a13..180de3ff281 100644
--- a/components/style/style_resolver.rs
+++ b/components/style/style_resolver.rs
@@ -233,7 +233,7 @@ where
 
         let mut pseudo_styles = EagerPseudoStyles::default();
 
-        if self.element.implemented_pseudo_element().is_none() {
+        if !self.element.is_pseudo_element() {
             let layout_parent_style_for_pseudo = if primary_style.style().is_display_contents() {
                 layout_parent_style
             } else {
@@ -293,10 +293,6 @@ where
         layout_parent_style: Option<&ComputedValues>,
         pseudo: Option<&PseudoElement>,
     ) -> ResolvedStyle {
-        debug_assert!(
-            self.element.implemented_pseudo_element().is_none() || pseudo.is_none(),
-            "Pseudo-elements can't have other pseudos!"
-        );
         debug_assert!(pseudo.map_or(true, |p| p.is_eager()));
 
         let implemented_pseudo = self.element.implemented_pseudo_element();
@@ -477,8 +473,8 @@ where
         );
         debug_assert!(pseudo_element.is_eager());
         debug_assert!(
-            self.element.implemented_pseudo_element().is_none(),
-            "Element pseudos can't have any other pseudo."
+            !self.element.is_pseudo_element(),
+            "Element pseudos can't have any other eager pseudo."
         );
 
         let mut applicable_declarations = ApplicableDeclarationList::new();
diff --git a/components/style/stylist.rs b/components/style/stylist.rs
index 2953e3f0671..cba1cbac524 100644
--- a/components/style/stylist.rs
+++ b/components/style/stylist.rs
@@ -1195,6 +1195,10 @@ impl Stylist {
         // See [3] for the bug to implement whatever gets resolved, and related
         // bugs for a bit more context.
         //
+        // FIXME(emilio): This should probably work for pseudo-elements (i.e.,
+        // use rule_hash_target().shadow_root() instead of
+        // element.shadow_root()).
+        //
         // [1]: https://cs.chromium.org/chromium/src/third_party/blink/renderer/
         //        core/css/resolver/style_resolver.cc?l=1267&rcl=90f9f8680ebb4a87d177f3b0833372ae4e0c88d8
         // [2]: https://github.com/w3c/csswg-drafts/issues/1995
diff --git a/components/style/values/animated/effects.rs b/components/style/values/animated/effects.rs
index 87f58fb2f82..4c559cd4c30 100644
--- a/components/style/values/animated/effects.rs
+++ b/components/style/values/animated/effects.rs
@@ -9,22 +9,18 @@ use crate::values::computed::length::Length;
 #[cfg(feature = "gecko")]
 use crate::values::computed::url::ComputedUrl;
 use crate::values::computed::{Angle, Number};
-use crate::values::generics::effects::BoxShadow as GenericBoxShadow;
 use crate::values::generics::effects::Filter as GenericFilter;
 use crate::values::generics::effects::SimpleShadow as GenericSimpleShadow;
 #[cfg(not(feature = "gecko"))]
 use crate::values::Impossible;
 
-/// An animated value for a single `box-shadow`.
-pub type BoxShadow = GenericBoxShadow<Color, Length, Length, Length>;
+/// An animated value for the `drop-shadow()` filter.
+pub type AnimatedSimpleShadow = GenericSimpleShadow<Color, Length, Length>;
 
 /// An animated value for a single `filter`.
 #[cfg(feature = "gecko")]
-pub type Filter = GenericFilter<Angle, Number, Length, SimpleShadow, ComputedUrl>;
+pub type Filter = GenericFilter<Angle, Number, Length, AnimatedSimpleShadow, ComputedUrl>;
 
 /// An animated value for a single `filter`.
 #[cfg(not(feature = "gecko"))]
 pub type Filter = GenericFilter<Angle, Number, Length, Impossible, Impossible>;
-
-/// An animated value for the `drop-shadow()` filter.
-pub type SimpleShadow = GenericSimpleShadow<Color, Length, Length>;
diff --git a/components/style/values/animated/transform.rs b/components/style/values/animated/transform.rs
index 0c322d8fccc..9ac64c3f2a7 100644
--- a/components/style/values/animated/transform.rs
+++ b/components/style/values/animated/transform.rs
@@ -861,7 +861,7 @@ impl Animate for ComputedTransform {
         // animation procedures so we treat it separately here rather than
         // handling it in TransformOperation.
         if procedure == Procedure::Add {
-            let result = self.0.iter().chain(&other.0).cloned().collect::<Vec<_>>();
+            let result = self.0.iter().chain(&*other.0).cloned().collect();
             return Ok(Transform(result));
         }
 
@@ -898,15 +898,15 @@ impl Animate for ComputedTransform {
                 },
                 Procedure::Interpolate { progress } => {
                     result.push(TransformOperation::InterpolateMatrix {
-                        from_list: Transform(this_remainder.to_vec()),
-                        to_list: Transform(other_remainder.to_vec()),
+                        from_list: Transform(this_remainder.to_vec().into()),
+                        to_list: Transform(other_remainder.to_vec().into()),
                         progress: Percentage(progress as f32),
                     });
                 },
                 Procedure::Accumulate { count } => {
                     result.push(TransformOperation::AccumulateMatrix {
-                        from_list: Transform(this_remainder.to_vec()),
-                        to_list: Transform(other_remainder.to_vec()),
+                        from_list: Transform(this_remainder.to_vec().into()),
+                        to_list: Transform(other_remainder.to_vec().into()),
                         count: cmp::min(count, i32::max_value() as u64) as i32,
                     });
                 },
@@ -927,8 +927,8 @@ impl Animate for ComputedTransform {
                                 // matrix. Instead we need to wrap it in another ___Matrix type.
                                 TransformOperation::AccumulateMatrix { .. } |
                                 TransformOperation::InterpolateMatrix { .. } => {
-                                    let transform_list = Transform(vec![transform.clone()]);
-                                    let identity_list = Transform(vec![identity]);
+                                    let transform_list = Transform(vec![transform.clone()].into());
+                                    let identity_list = Transform(vec![identity].into());
                                     let (from_list, to_list) = if fill_right {
                                         (transform_list, identity_list)
                                     } else {
@@ -970,7 +970,7 @@ impl Animate for ComputedTransform {
             (None, None) => {},
         }
 
-        Ok(Transform(result))
+        Ok(Transform(result.into()))
     }
 }
 
diff --git a/components/style/values/computed/angle.rs b/components/style/values/computed/angle.rs
index cdbc0006941..d8cdefb5263 100644
--- a/components/style/values/computed/angle.rs
+++ b/components/style/values/computed/angle.rs
@@ -26,6 +26,7 @@ use style_traits::{CssWriter, ToCss};
     ToAnimatedZero,
     ToResolvedValue,
 )]
+#[repr(C)]
 pub struct Angle(CSSFloat);
 
 impl ToCss for Angle {
diff --git a/components/style/values/computed/border.rs b/components/style/values/computed/border.rs
index 62c8e3883f6..abdc28ad848 100644
--- a/components/style/values/computed/border.rs
+++ b/components/style/values/computed/border.rs
@@ -7,10 +7,10 @@
 use crate::values::computed::length::{NonNegativeLength, NonNegativeLengthPercentage};
 use crate::values::computed::{NonNegativeNumber, NonNegativeNumberOrPercentage};
 use crate::values::generics::border::BorderCornerRadius as GenericBorderCornerRadius;
-use crate::values::generics::border::BorderImageSideWidth as GenericBorderImageSideWidth;
 use crate::values::generics::border::BorderImageSlice as GenericBorderImageSlice;
 use crate::values::generics::border::BorderRadius as GenericBorderRadius;
 use crate::values::generics::border::BorderSpacing as GenericBorderSpacing;
+use crate::values::generics::border::GenericBorderImageSideWidth;
 use crate::values::generics::rect::Rect;
 use crate::values::generics::size::Size2D;
 use crate::values::generics::NonNegative;
diff --git a/components/style/values/computed/gecko.rs b/components/style/values/computed/gecko.rs
deleted file mode 100644
index cbe0802eab8..00000000000
--- a/components/style/values/computed/gecko.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-//! Computed types for legacy Gecko-only properties.
-
-use crate::values::computed::length::LengthPercentage;
-use crate::values::generics::gecko::ScrollSnapPoint as GenericScrollSnapPoint;
-
-/// A computed type for scroll snap points.
-pub type ScrollSnapPoint = GenericScrollSnapPoint<LengthPercentage>;
diff --git a/components/style/values/computed/list.rs b/components/style/values/computed/list.rs
index 2bde35e3b6b..3536aa656fe 100644
--- a/components/style/values/computed/list.rs
+++ b/components/style/values/computed/list.rs
@@ -9,21 +9,19 @@ pub use crate::values::specified::list::ListStyleType;
 pub use crate::values::specified::list::MozListReversed;
 pub use crate::values::specified::list::{QuotePair, Quotes};
 
-use servo_arc::Arc;
-
 lazy_static! {
-    static ref INITIAL_QUOTES: Arc<Box<[QuotePair]>> = Arc::new(
+    static ref INITIAL_QUOTES: crate::ArcSlice<QuotePair> = crate::ArcSlice::from_iter(
         vec![
             QuotePair {
-                opening: "\u{201c}".to_owned().into_boxed_str(),
-                closing: "\u{201d}".to_owned().into_boxed_str(),
+                opening: "\u{201c}".to_owned().into(),
+                closing: "\u{201d}".to_owned().into(),
             },
             QuotePair {
-                opening: "\u{2018}".to_owned().into_boxed_str(),
-                closing: "\u{2019}".to_owned().into_boxed_str(),
+                opening: "\u{2018}".to_owned().into(),
+                closing: "\u{2019}".to_owned().into(),
             },
         ]
-        .into_boxed_slice()
+        .into_iter()
     );
 }
 
diff --git a/components/style/values/computed/mod.rs b/components/style/values/computed/mod.rs
index 5bf0333dbfe..06579238e77 100644
--- a/components/style/values/computed/mod.rs
+++ b/components/style/values/computed/mod.rs
@@ -56,8 +56,6 @@ pub use self::font::{FontSize, FontSizeAdjust, FontStretch, FontSynthesis};
 pub use self::font::{FontVariantAlternates, FontWeight};
 pub use self::font::{FontVariantEastAsian, FontVariationSettings};
 pub use self::font::{MozScriptLevel, MozScriptMinSize, MozScriptSizeMultiplier, XLang, XTextZoom};
-#[cfg(feature = "gecko")]
-pub use self::gecko::ScrollSnapPoint;
 pub use self::image::{Gradient, GradientItem, Image, ImageLayer, LineDirection, MozImageRect};
 pub use self::length::{CSSPixelLength, ExtremumLength, NonNegativeLength};
 pub use self::length::{Length, LengthOrNumber, LengthPercentage, NonNegativeLengthOrNumber};
@@ -67,7 +65,7 @@ pub use self::length::{NonNegativeLengthPercentage, NonNegativeLengthPercentageO
 pub use self::list::ListStyleType;
 pub use self::list::MozListReversed;
 pub use self::list::{QuotePair, Quotes};
-pub use self::motion::OffsetPath;
+pub use self::motion::{OffsetPath, OffsetRotate};
 pub use self::outline::OutlineStyle;
 pub use self::percentage::{NonNegativePercentage, Percentage};
 pub use self::position::{GridAutoFlow, GridTemplateAreas, Position, ZIndex};
@@ -77,7 +75,7 @@ pub use self::svg::MozContextProperties;
 pub use self::svg::{SVGLength, SVGOpacity, SVGPaint, SVGPaintKind};
 pub use self::svg::{SVGPaintOrder, SVGStrokeDashArray, SVGWidth};
 pub use self::table::XSpan;
-pub use self::text::{InitialLetter, LetterSpacing, LineHeight};
+pub use self::text::{InitialLetter, LetterSpacing, LineBreak, LineHeight};
 pub use self::text::{OverflowWrap, TextOverflow, WordBreak, WordSpacing};
 pub use self::text::{TextAlign, TextEmphasisPosition, TextEmphasisStyle};
 pub use self::time::Time;
@@ -106,8 +104,6 @@ pub mod easing;
 pub mod effects;
 pub mod flex;
 pub mod font;
-#[cfg(feature = "gecko")]
-pub mod gecko;
 pub mod image;
 pub mod length;
 pub mod list;
@@ -454,17 +450,12 @@ where
     fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
         self.iter()
             .map(|item| item.to_computed_value(context))
-            .collect::<Vec<_>>()
-            .into()
+            .collect()
     }
 
     #[inline]
     fn from_computed_value(computed: &Self::ComputedValue) -> Self {
-        computed
-            .iter()
-            .map(T::from_computed_value)
-            .collect::<Vec<_>>()
-            .into()
+        computed.iter().map(T::from_computed_value).collect()
     }
 }
 
diff --git a/components/style/values/computed/motion.rs b/components/style/values/computed/motion.rs
index a5f1fa885c3..932d8074262 100644
--- a/components/style/values/computed/motion.rs
+++ b/components/style/values/computed/motion.rs
@@ -4,7 +4,41 @@
 
 //! Computed types for CSS values that are related to motion path.
 
+use crate::values::computed::Angle;
+use crate::Zero;
+
 /// A computed offset-path. The computed value is as specified value.
 ///
 /// https://drafts.fxtf.org/motion-1/#offset-path-property
 pub use crate::values::specified::motion::OffsetPath;
+
+#[inline]
+fn is_auto_zero_angle(auto: &bool, angle: &Angle) -> bool {
+    *auto && angle.is_zero()
+}
+
+/// A computed offset-rotate.
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss, ToResolvedValue)]
+#[repr(C)]
+pub struct OffsetRotate {
+    /// If auto is false, this is a fixed angle which indicates a
+    /// constant clockwise rotation transformation applied to it by this
+    /// specified rotation angle. Otherwise, the angle will be added to
+    /// the angle of the direction in layout.
+    #[css(represents_keyword)]
+    pub auto: bool,
+    /// The angle value.
+    #[css(contextual_skip_if = "is_auto_zero_angle")]
+    pub angle: Angle,
+}
+
+impl OffsetRotate {
+    /// Returns "auto 0deg".
+    #[inline]
+    pub fn auto() -> Self {
+        OffsetRotate {
+            auto: true,
+            angle: Zero::zero(),
+        }
+    }
+}
diff --git a/components/style/values/computed/text.rs b/components/style/values/computed/text.rs
index c29d3d45210..bc4086a2b9c 100644
--- a/components/style/values/computed/text.rs
+++ b/components/style/values/computed/text.rs
@@ -20,7 +20,7 @@ use style_traits::{CssWriter, ToCss};
 
 pub use crate::values::specified::TextAlignKeyword as TextAlign;
 pub use crate::values::specified::TextTransform;
-pub use crate::values::specified::{OverflowWrap, WordBreak};
+pub use crate::values::specified::{LineBreak, OverflowWrap, WordBreak};
 pub use crate::values::specified::{TextDecorationLine, TextEmphasisPosition};
 
 /// A computed value for the `initial-letter` property.
@@ -105,6 +105,7 @@ impl ToComputedValue for specified::WordSpacing {
 pub type LineHeight = GenericLineHeight<NonNegativeNumber, NonNegativeLength>;
 
 #[derive(Clone, Debug, MallocSizeOf, PartialEq, ToResolvedValue)]
+#[repr(C)]
 /// text-overflow.
 /// When the specified value only has one side, that's the "second"
 /// side, and the sides are logical, so "second" means "end".  The
diff --git a/components/style/values/computed/transform.rs b/components/style/values/computed/transform.rs
index e23ec1524ff..9104a43ae5b 100644
--- a/components/style/values/computed/transform.rs
+++ b/components/style/values/computed/transform.rs
@@ -16,9 +16,9 @@ pub use crate::values::generics::transform::TransformStyle;
 
 /// A single operation in a computed CSS `transform`
 pub type TransformOperation =
-    generic::TransformOperation<Angle, Number, Length, Integer, LengthPercentage>;
+    generic::GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>;
 /// A computed CSS `transform`
-pub type Transform = generic::Transform<TransformOperation>;
+pub type Transform = generic::GenericTransform<TransformOperation>;
 
 /// The computed value of a CSS `<transform-origin>`
 pub type TransformOrigin =
@@ -540,88 +540,16 @@ impl ToAnimatedZero for Transform {
             self.0
                 .iter()
                 .map(|op| op.to_animated_zero())
-                .collect::<Result<Vec<_>, _>>()?,
+                .collect::<Result<crate::OwnedSlice<_>, _>>()?,
         ))
     }
 }
 
 /// A computed CSS `rotate`
-pub type Rotate = generic::Rotate<Number, Angle>;
-
-impl Rotate {
-    /// Convert TransformOperation to Rotate.
-    pub fn to_transform_operation(&self) -> Option<TransformOperation> {
-        match *self {
-            generic::Rotate::None => None,
-            generic::Rotate::Rotate(angle) => Some(generic::TransformOperation::Rotate(angle)),
-            generic::Rotate::Rotate3D(rx, ry, rz, angle) => {
-                Some(generic::TransformOperation::Rotate3D(rx, ry, rz, angle))
-            },
-        }
-    }
-
-    /// Convert Rotate to TransformOperation.
-    pub fn from_transform_operation(operation: &TransformOperation) -> Rotate {
-        match *operation {
-            generic::TransformOperation::Rotate(angle) => generic::Rotate::Rotate(angle),
-            generic::TransformOperation::Rotate3D(rx, ry, rz, angle) => {
-                generic::Rotate::Rotate3D(rx, ry, rz, angle)
-            },
-            _ => unreachable!("Found unexpected value for rotate property"),
-        }
-    }
-}
+pub type Rotate = generic::GenericRotate<Number, Angle>;
 
 /// A computed CSS `translate`
-pub type Translate = generic::Translate<LengthPercentage, Length>;
-
-impl Translate {
-    /// Convert TransformOperation to Translate.
-    pub fn to_transform_operation(&self) -> Option<TransformOperation> {
-        match *self {
-            generic::Translate::None => None,
-            generic::Translate::Translate(tx, ty) => {
-                Some(generic::TransformOperation::Translate(tx, ty))
-            },
-            generic::Translate::Translate3D(tx, ty, tz) => {
-                Some(generic::TransformOperation::Translate3D(tx, ty, tz))
-            },
-        }
-    }
-
-    /// Convert Translate to TransformOperation.
-    pub fn from_transform_operation(operation: &TransformOperation) -> Translate {
-        match *operation {
-            generic::TransformOperation::Translate(tx, ty) => generic::Translate::Translate(tx, ty),
-            generic::TransformOperation::Translate3D(tx, ty, tz) => {
-                generic::Translate::Translate3D(tx, ty, tz)
-            },
-            _ => unreachable!("Found unexpected value for translate"),
-        }
-    }
-}
+pub type Translate = generic::GenericTranslate<LengthPercentage, Length>;
 
 /// A computed CSS `scale`
-pub type Scale = generic::Scale<Number>;
-
-impl Scale {
-    /// Convert TransformOperation to Scale.
-    pub fn to_transform_operation(&self) -> Option<TransformOperation> {
-        match *self {
-            generic::Scale::None => None,
-            generic::Scale::Scale(sx, sy) => Some(generic::TransformOperation::Scale(sx, sy)),
-            generic::Scale::Scale3D(sx, sy, sz) => {
-                Some(generic::TransformOperation::Scale3D(sx, sy, sz))
-            },
-        }
-    }
-
-    /// Convert Scale to TransformOperation.
-    pub fn from_transform_operation(operation: &TransformOperation) -> Scale {
-        match *operation {
-            generic::TransformOperation::Scale(sx, sy) => generic::Scale::Scale(sx, sy),
-            generic::TransformOperation::Scale3D(sx, sy, sz) => generic::Scale::Scale3D(sx, sy, sz),
-            _ => unreachable!("Found unexpected value for scale"),
-        }
-    }
-}
+pub type Scale = generic::GenericScale<Number>;
diff --git a/components/style/values/generics/border.rs b/components/style/values/generics/border.rs
index ec0ab1c4b07..f36062ce39b 100644
--- a/components/style/values/generics/border.rs
+++ b/components/style/values/generics/border.rs
@@ -23,15 +23,18 @@ use style_traits::{CssWriter, ToCss};
     ToResolvedValue,
     ToShmem,
 )]
-pub enum BorderImageSideWidth<LengthPercentage, Number> {
+#[repr(C, u8)]
+pub enum GenericBorderImageSideWidth<LP, N> {
     /// `<length-or-percentage>`
-    Length(LengthPercentage),
+    LengthPercentage(LP),
     /// `<number>`
-    Number(Number),
+    Number(N),
     /// `auto`
     Auto,
 }
 
+pub use self::GenericBorderImageSideWidth as BorderImageSideWidth;
+
 /// A generic value for the `border-image-slice` property.
 #[derive(
     Clone,
diff --git a/components/style/values/generics/effects.rs b/components/style/values/generics/effects.rs
index aa56fc1bbb3..a27adc49e52 100644
--- a/components/style/values/generics/effects.rs
+++ b/components/style/values/generics/effects.rs
@@ -19,9 +19,10 @@
     ToResolvedValue,
     ToShmem,
 )]
-pub struct BoxShadow<Color, SizeLength, BlurShapeLength, ShapeLength> {
+#[repr(C)]
+pub struct GenericBoxShadow<Color, SizeLength, BlurShapeLength, ShapeLength> {
     /// The base shadow.
-    pub base: SimpleShadow<Color, SizeLength, BlurShapeLength>,
+    pub base: GenericSimpleShadow<Color, SizeLength, BlurShapeLength>,
     /// The spread radius.
     pub spread: ShapeLength,
     /// Whether this is an inset box shadow.
@@ -30,6 +31,8 @@ pub struct BoxShadow<Color, SizeLength, BlurShapeLength, ShapeLength> {
     pub inset: bool,
 }
 
+pub use self::GenericBoxShadow as BoxShadow;
+
 /// A generic value for a single `filter`.
 #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
 #[animation(no_bound(Url))]
@@ -100,7 +103,8 @@ pub enum Filter<Angle, Factor, Length, DropShadow, Url> {
     ToResolvedValue,
     ToShmem,
 )]
-pub struct SimpleShadow<Color, SizeLength, ShapeLength> {
+#[repr(C)]
+pub struct GenericSimpleShadow<Color, SizeLength, ShapeLength> {
     /// Color.
     pub color: Color,
     /// Horizontal radius.
@@ -110,3 +114,5 @@ pub struct SimpleShadow<Color, SizeLength, ShapeLength> {
     /// Blur radius.
     pub blur: ShapeLength,
 }
+
+pub use self::GenericSimpleShadow as SimpleShadow;
diff --git a/components/style/values/generics/gecko.rs b/components/style/values/generics/gecko.rs
deleted file mode 100644
index ccff3d2a76d..00000000000
--- a/components/style/values/generics/gecko.rs
+++ /dev/null
@@ -1,44 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-//! Generic types for legacy Gecko-only properties that should probably be
-//! un-shipped at some point in the future.
-
-/// A generic value for scroll snap points.
-#[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-#[derive(
-    Clone,
-    Copy,
-    Debug,
-    PartialEq,
-    SpecifiedValueInfo,
-    ToComputedValue,
-    ToCss,
-    ToResolvedValue,
-    ToShmem,
-)]
-pub enum ScrollSnapPoint<LengthPercentage> {
-    /// `none`
-    None,
-    /// `repeat(<length-or-percentage>)`
-    #[css(function)]
-    Repeat(LengthPercentage),
-}
-
-impl<L> ScrollSnapPoint<L> {
-    /// Returns `none`.
-    #[inline]
-    pub fn none() -> Self {
-        ScrollSnapPoint::None
-    }
-
-    /// Returns the repeat argument, if any.
-    #[inline]
-    pub fn repeated(&self) -> Option<&L> {
-        match *self {
-            ScrollSnapPoint::None => None,
-            ScrollSnapPoint::Repeat(ref length) => Some(length),
-        }
-    }
-}
diff --git a/components/style/values/generics/mod.rs b/components/style/values/generics/mod.rs
index d735e3bbdef..08ae15a4c2c 100644
--- a/components/style/values/generics/mod.rs
+++ b/components/style/values/generics/mod.rs
@@ -26,8 +26,6 @@ pub mod easing;
 pub mod effects;
 pub mod flex;
 pub mod font;
-#[cfg(feature = "gecko")]
-pub mod gecko;
 pub mod grid;
 pub mod image;
 pub mod length;
diff --git a/components/style/values/generics/transform.rs b/components/style/values/generics/transform.rs
index 6c6374db941..ba0e320865a 100644
--- a/components/style/values/generics/transform.rs
+++ b/components/style/values/generics/transform.rs
@@ -30,8 +30,9 @@ use style_traits::{CssWriter, ToCss};
     ToResolvedValue,
     ToShmem,
 )]
-#[css(comma, function)]
-pub struct Matrix<T> {
+#[css(comma, function = "matrix")]
+#[repr(C)]
+pub struct GenericMatrix<T> {
     pub a: T,
     pub b: T,
     pub c: T,
@@ -40,6 +41,8 @@ pub struct Matrix<T> {
     pub f: T,
 }
 
+pub use self::GenericMatrix as Matrix;
+
 #[allow(missing_docs)]
 #[cfg_attr(rustfmt, rustfmt_skip)]
 #[css(comma, function = "matrix3d")]
@@ -55,13 +58,16 @@ pub struct Matrix<T> {
     ToResolvedValue,
     ToShmem,
 )]
-pub struct Matrix3D<T> {
+#[repr(C)]
+pub struct GenericMatrix3D<T> {
     pub m11: T, pub m12: T, pub m13: T, pub m14: T,
     pub m21: T, pub m22: T, pub m23: T, pub m24: T,
     pub m31: T, pub m32: T, pub m33: T, pub m34: T,
     pub m41: T, pub m42: T, pub m43: T, pub m44: T,
 }
 
+pub use self::GenericMatrix3D as Matrix3D;
+
 #[cfg_attr(rustfmt, rustfmt_skip)]
 impl<T: Into<f64>> From<Matrix<T>> for Transform3D<f64> {
     #[inline]
@@ -142,17 +148,19 @@ fn is_same<N: PartialEq>(x: &N, y: &N) -> bool {
     ToResolvedValue,
     ToShmem,
 )]
+#[repr(C, u8)]
 /// A single operation in the list of a `transform` value
-pub enum TransformOperation<Angle, Number, Length, Integer, LengthPercentage>
+/// cbindgen:derive-tagged-enum-copy-constructor=true
+pub enum GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>
 where
     Angle: Zero,
     LengthPercentage: Zero,
     Number: PartialEq,
 {
     /// Represents a 2D 2x3 matrix.
-    Matrix(Matrix<Number>),
+    Matrix(GenericMatrix<Number>),
     /// Represents a 3D 4x4 matrix.
-    Matrix3D(Matrix3D<Number>),
+    Matrix3D(GenericMatrix3D<Number>),
     /// A 2D skew.
     ///
     /// If the second angle is not provided it is assumed zero.
@@ -232,20 +240,30 @@ where
     #[allow(missing_docs)]
     #[css(comma, function = "interpolatematrix")]
     InterpolateMatrix {
-        from_list: Transform<TransformOperation<Angle, Number, Length, Integer, LengthPercentage>>,
-        to_list: Transform<TransformOperation<Angle, Number, Length, Integer, LengthPercentage>>,
+        from_list: GenericTransform<
+            GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>,
+        >,
+        to_list: GenericTransform<
+            GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>,
+        >,
         progress: computed::Percentage,
     },
     /// A intermediate type for accumulation of mismatched transform lists.
     #[allow(missing_docs)]
     #[css(comma, function = "accumulatematrix")]
     AccumulateMatrix {
-        from_list: Transform<TransformOperation<Angle, Number, Length, Integer, LengthPercentage>>,
-        to_list: Transform<TransformOperation<Angle, Number, Length, Integer, LengthPercentage>>,
+        from_list: GenericTransform<
+            GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>,
+        >,
+        to_list: GenericTransform<
+            GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>,
+        >,
         count: Integer,
     },
 }
 
+pub use self::GenericTransformOperation as TransformOperation;
+
 #[derive(
     Clone,
     Debug,
@@ -257,8 +275,11 @@ where
     ToResolvedValue,
     ToShmem,
 )]
+#[repr(C)]
 /// A value of the `transform` property
-pub struct Transform<T>(#[css(if_empty = "none", iterable)] pub Vec<T>);
+pub struct GenericTransform<T>(#[css(if_empty = "none", iterable)] pub crate::OwnedSlice<T>);
+
+pub use self::GenericTransform as Transform;
 
 impl<Angle, Number, Length, Integer, LengthPercentage>
     TransformOperation<Angle, Number, Length, Integer, LengthPercentage>
@@ -497,7 +518,7 @@ where
 impl<T> Transform<T> {
     /// `none`
     pub fn none() -> Self {
-        Transform(vec![])
+        Transform(Default::default())
     }
 }
 
@@ -529,7 +550,7 @@ impl<T: ToMatrix> Transform<T> {
         let mut transform = Transform3D::<f64>::identity();
         let mut contain_3d = false;
 
-        for operation in &self.0 {
+        for operation in &*self.0 {
             let matrix = operation.to_3d_matrix(reference_box)?;
             contain_3d |= operation.is_3d();
             transform = transform.pre_mul(&matrix);
@@ -589,10 +610,11 @@ pub fn get_normalized_vector_and_angle<T: Zero>(
     ToResolvedValue,
     ToShmem,
 )]
+#[repr(C, u8)]
 /// A value of the `Rotate` property
 ///
 /// <https://drafts.csswg.org/css-transforms-2/#individual-transforms>
-pub enum Rotate<Number, Angle> {
+pub enum GenericRotate<Number, Angle> {
     /// 'none'
     None,
     /// '<angle>'
@@ -601,6 +623,8 @@ pub enum Rotate<Number, Angle> {
     Rotate3D(Number, Number, Number, Angle),
 }
 
+pub use self::GenericRotate as Rotate;
+
 /// A trait to check if the current 3D vector is parallel to the DirectionVector.
 /// This is especially for serialization on Rotate.
 pub trait IsParallelTo {
@@ -660,10 +684,11 @@ where
     ToResolvedValue,
     ToShmem,
 )]
+#[repr(C, u8)]
 /// A value of the `Scale` property
 ///
 /// <https://drafts.csswg.org/css-transforms-2/#individual-transforms>
-pub enum Scale<Number> {
+pub enum GenericScale<Number> {
     /// 'none'
     None,
     /// '<number>{1,2}'
@@ -672,6 +697,8 @@ pub enum Scale<Number> {
     Scale3D(Number, Number, Number),
 }
 
+pub use self::GenericScale as Scale;
+
 impl<Number: ToCss + PartialEq> ToCss for Scale<Number> {
     fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
     where
@@ -710,6 +737,7 @@ impl<Number: ToCss + PartialEq> ToCss for Scale<Number> {
     ToResolvedValue,
     ToShmem,
 )]
+#[repr(C, u8)]
 /// A value of the `translate` property
 ///
 /// https://drafts.csswg.org/css-transforms-2/#individual-transform-serialization:
@@ -724,7 +752,7 @@ impl<Number: ToCss + PartialEq> ToCss for Scale<Number> {
 /// related spec issue is https://github.com/w3c/csswg-drafts/issues/3305
 ///
 /// <https://drafts.csswg.org/css-transforms-2/#individual-transforms>
-pub enum Translate<LengthPercentage, Length>
+pub enum GenericTranslate<LengthPercentage, Length>
 where
     LengthPercentage: Zero,
 {
@@ -739,6 +767,8 @@ where
     Translate3D(LengthPercentage, LengthPercentage, Length),
 }
 
+pub use self::GenericTranslate as Translate;
+
 #[allow(missing_docs)]
 #[derive(
     Clone,
diff --git a/components/style/values/mod.rs b/components/style/values/mod.rs
index e2da4984084..36ea909ab87 100644
--- a/components/style/values/mod.rs
+++ b/components/style/values/mod.rs
@@ -174,6 +174,7 @@ impl<A: Debug, B: Debug> Debug for Either<A, B> {
     ToResolvedValue,
     ToShmem,
 )]
+#[repr(C)]
 pub struct CustomIdent(pub Atom);
 
 impl CustomIdent {
diff --git a/components/style/values/specified/border.rs b/components/style/values/specified/border.rs
index 59f2f7aa284..338b0d18c27 100644
--- a/components/style/values/specified/border.rs
+++ b/components/style/values/specified/border.rs
@@ -183,7 +183,7 @@ impl Parse for BorderImageSideWidth {
         }
 
         if let Ok(len) = input.try(|i| NonNegativeLengthPercentage::parse(context, i)) {
-            return Ok(GenericBorderImageSideWidth::Length(len));
+            return Ok(GenericBorderImageSideWidth::LengthPercentage(len));
         }
 
         let num = NonNegativeNumber::parse(context, input)?;
diff --git a/components/style/values/specified/box.rs b/components/style/values/specified/box.rs
index 31a79c141e1..542976d45ba 100644
--- a/components/style/values/specified/box.rs
+++ b/components/style/values/specified/box.rs
@@ -642,6 +642,7 @@ pub enum OverflowClipBox {
 #[derive(
     Clone,
     Debug,
+    Default,
     MallocSizeOf,
     PartialEq,
     SpecifiedValueInfo,
@@ -650,38 +651,38 @@ pub enum OverflowClipBox {
     ToResolvedValue,
     ToShmem,
 )]
-/// Provides a rendering hint to the user agent,
-/// stating what kinds of changes the author expects
-/// to perform on the element
+#[css(comma)]
+#[repr(C)]
+/// Provides a rendering hint to the user agent, stating what kinds of changes
+/// the author expects to perform on the element.
+///
+/// `auto` is represented by an empty `features` list.
 ///
 /// <https://drafts.csswg.org/css-will-change/#will-change>
-pub enum WillChange {
-    /// Expresses no particular intent
-    Auto,
-    /// <custom-ident>
-    #[css(comma)]
-    AnimateableFeatures {
-        /// The features that are supposed to change.
-        #[css(iterable)]
-        features: Box<[CustomIdent]>,
-        /// A bitfield with the kind of change that the value will create, based
-        /// on the above field.
-        #[css(skip)]
-        bits: WillChangeBits,
-    },
+pub struct WillChange {
+    /// The features that are supposed to change.
+    ///
+    /// TODO(emilio): Consider using ArcSlice since we just clone them from the
+    /// specified value? That'd save an allocation, which could be worth it.
+    #[css(iterable, if_empty = "auto")]
+    features: crate::OwnedSlice<CustomIdent>,
+    /// A bitfield with the kind of change that the value will create, based
+    /// on the above field.
+    #[css(skip)]
+    bits: WillChangeBits,
 }
 
 impl WillChange {
     #[inline]
     /// Get default value of `will-change` as `auto`
-    pub fn auto() -> WillChange {
-        WillChange::Auto
+    pub fn auto() -> Self {
+        Self::default()
     }
 }
 
 bitflags! {
     /// The change bits that we care about.
-    #[derive(MallocSizeOf, SpecifiedValueInfo, ToComputedValue, ToResolvedValue, ToShmem)]
+    #[derive(Default, MallocSizeOf, SpecifiedValueInfo, ToComputedValue, ToResolvedValue, ToShmem)]
     #[repr(C)]
     pub struct WillChangeBits: u8 {
         /// Whether the stacking context will change.
@@ -746,7 +747,7 @@ impl Parse for WillChange {
             .try(|input| input.expect_ident_matching("auto"))
             .is_ok()
         {
-            return Ok(WillChange::Auto);
+            return Ok(Self::default());
         }
 
         let mut bits = WillChangeBits::empty();
@@ -767,8 +768,8 @@ impl Parse for WillChange {
             Ok(ident)
         })?;
 
-        Ok(WillChange::AnimateableFeatures {
-            features: custom_idents.into_boxed_slice(),
+        Ok(Self {
+            features: custom_idents.into(),
             bits,
         })
     }
diff --git a/components/style/values/specified/effects.rs b/components/style/values/specified/effects.rs
index d8c378a8a7b..3ffad2fa89c 100644
--- a/components/style/values/specified/effects.rs
+++ b/components/style/values/specified/effects.rs
@@ -17,7 +17,7 @@ use crate::values::specified::color::Color;
 use crate::values::specified::length::{Length, NonNegativeLength};
 #[cfg(feature = "gecko")]
 use crate::values::specified::url::SpecifiedUrl;
-use crate::values::specified::{Angle, NumberOrPercentage};
+use crate::values::specified::{Angle, Number, NumberOrPercentage};
 #[cfg(not(feature = "gecko"))]
 use crate::values::Impossible;
 use crate::Zero;
@@ -62,6 +62,10 @@ impl Factor {
             },
         }
     }
+
+    fn one() -> Self {
+        Factor(NumberOrPercentage::Number(Number::new(1.0)))
+    }
 }
 
 impl Parse for Factor {
@@ -209,34 +213,61 @@ impl Parse for Filter {
         };
         input.parse_nested_block(|i| {
             match_ignore_ascii_case! { &*function,
-                "blur" => Ok(GenericFilter::Blur((Length::parse_non_negative(context, i)?).into())),
-                "brightness" => Ok(GenericFilter::Brightness(Factor::parse(context, i)?)),
-                "contrast" => Ok(GenericFilter::Contrast(Factor::parse(context, i)?)),
+                "blur" => Ok(GenericFilter::Blur(
+                    i.try(|i| NonNegativeLength::parse(context, i))
+                     .unwrap_or(Zero::zero()),
+                )),
+                "brightness" => Ok(GenericFilter::Brightness(
+                    i.try(|i| Factor::parse(context, i))
+                     .unwrap_or(Factor::one()),
+                )),
+                "contrast" => Ok(GenericFilter::Contrast(
+                    i.try(|i| Factor::parse(context, i))
+                     .unwrap_or(Factor::one()),
+                )),
                 "grayscale" => {
                     // Values of amount over 100% are allowed but UAs must clamp the values to 1.
                     // https://drafts.fxtf.org/filter-effects/#funcdef-filter-grayscale
-                    Ok(GenericFilter::Grayscale(Factor::parse_with_clamping_to_one(context, i)?))
+                    Ok(GenericFilter::Grayscale(
+                        i.try(|i| Factor::parse_with_clamping_to_one(context, i))
+                         .unwrap_or(Factor::one()),
+                    ))
                 },
                 "hue-rotate" => {
                     // We allow unitless zero here, see:
                     // https://github.com/w3c/fxtf-drafts/issues/228
-                    Ok(GenericFilter::HueRotate(Angle::parse_with_unitless(context, i)?))
+                    Ok(GenericFilter::HueRotate(
+                        i.try(|i| Angle::parse_with_unitless(context, i))
+                         .unwrap_or(Zero::zero()),
+                    ))
                 },
                 "invert" => {
                     // Values of amount over 100% are allowed but UAs must clamp the values to 1.
                     // https://drafts.fxtf.org/filter-effects/#funcdef-filter-invert
-                    Ok(GenericFilter::Invert(Factor::parse_with_clamping_to_one(context, i)?))
+                    Ok(GenericFilter::Invert(
+                        i.try(|i| Factor::parse_with_clamping_to_one(context, i))
+                         .unwrap_or(Factor::one()),
+                    ))
                 },
                 "opacity" => {
                     // Values of amount over 100% are allowed but UAs must clamp the values to 1.
                     // https://drafts.fxtf.org/filter-effects/#funcdef-filter-opacity
-                    Ok(GenericFilter::Opacity(Factor::parse_with_clamping_to_one(context, i)?))
+                    Ok(GenericFilter::Opacity(
+                        i.try(|i| Factor::parse_with_clamping_to_one(context, i))
+                         .unwrap_or(Factor::one()),
+                    ))
                 },
-                "saturate" => Ok(GenericFilter::Saturate(Factor::parse(context, i)?)),
+                "saturate" => Ok(GenericFilter::Saturate(
+                    i.try(|i| Factor::parse(context, i))
+                     .unwrap_or(Factor::one()),
+                )),
                 "sepia" => {
                     // Values of amount over 100% are allowed but UAs must clamp the values to 1.
                     // https://drafts.fxtf.org/filter-effects/#funcdef-filter-sepia
-                    Ok(GenericFilter::Sepia(Factor::parse_with_clamping_to_one(context, i)?))
+                    Ok(GenericFilter::Sepia(
+                        i.try(|i| Factor::parse_with_clamping_to_one(context, i))
+                         .unwrap_or(Factor::one()),
+                    ))
                 },
                 "drop-shadow" => Ok(GenericFilter::DropShadow(Parse::parse(context, i)?)),
                 _ => Err(location.new_custom_error(
diff --git a/components/style/values/specified/gecko.rs b/components/style/values/specified/gecko.rs
index 42ca5e3e2bf..131c2a1a314 100644
--- a/components/style/values/specified/gecko.rs
+++ b/components/style/values/specified/gecko.rs
@@ -7,33 +7,12 @@
 use crate::parser::{Parse, ParserContext};
 use crate::values::computed::length::CSSPixelLength;
 use crate::values::computed::{self, LengthPercentage};
-use crate::values::generics::gecko::ScrollSnapPoint as GenericScrollSnapPoint;
 use crate::values::generics::rect::Rect;
-use crate::values::specified::length::LengthPercentage as SpecifiedLengthPercentage;
 use cssparser::{Parser, Token};
 use std::fmt;
 use style_traits::values::SequenceWriter;
 use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 
-/// A specified type for scroll snap points.
-pub type ScrollSnapPoint = GenericScrollSnapPoint<SpecifiedLengthPercentage>;
-
-impl Parse for ScrollSnapPoint {
-    fn parse<'i, 't>(
-        context: &ParserContext,
-        input: &mut Parser<'i, 't>,
-    ) -> Result<Self, ParseError<'i>> {
-        if input.try(|i| i.expect_ident_matching("none")).is_ok() {
-            return Ok(GenericScrollSnapPoint::None);
-        }
-        input.expect_function_matching("repeat")?;
-        // FIXME(emilio): This won't clamp properly when animating.
-        let length = input
-            .parse_nested_block(|i| SpecifiedLengthPercentage::parse_non_negative(context, i))?;
-        Ok(GenericScrollSnapPoint::Repeat(length))
-    }
-}
-
 fn parse_pixel_or_percent<'i, 't>(
     _context: &ParserContext,
     input: &mut Parser<'i, 't>,
diff --git a/components/style/values/specified/list.rs b/components/style/values/specified/list.rs
index 8c1e9fa2ad4..0519053b902 100644
--- a/components/style/values/specified/list.rs
+++ b/components/style/values/specified/list.rs
@@ -10,7 +10,6 @@ use crate::values::generics::CounterStyleOrNone;
 #[cfg(feature = "gecko")]
 use crate::values::CustomIdent;
 use cssparser::{Parser, Token};
-use servo_arc::Arc;
 use style_traits::{ParseError, StyleParseErrorKind};
 
 /// Specified and computed `list-style-type` property.
@@ -96,18 +95,20 @@ impl Parse for ListStyleType {
     ToResolvedValue,
     ToShmem,
 )]
+#[repr(C)]
 pub struct QuotePair {
     /// The opening quote.
-    pub opening: Box<str>,
+    pub opening: crate::OwnedStr,
 
     /// The closing quote.
-    pub closing: Box<str>,
+    pub closing: crate::OwnedStr,
 }
 
 /// Specified and computed `quotes` property.
 #[derive(
     Clone,
     Debug,
+    Default,
     MallocSizeOf,
     PartialEq,
     SpecifiedValueInfo,
@@ -116,10 +117,11 @@ pub struct QuotePair {
     ToResolvedValue,
     ToShmem,
 )]
+#[repr(C)]
 pub struct Quotes(
     #[css(iterable, if_empty = "none")]
     #[ignore_malloc_size_of = "Arc"]
-    pub Arc<Box<[QuotePair]>>,
+    pub crate::ArcSlice<QuotePair>,
 );
 
 impl Parse for Quotes {
@@ -131,24 +133,24 @@ impl Parse for Quotes {
             .try(|input| input.expect_ident_matching("none"))
             .is_ok()
         {
-            return Ok(Quotes(Arc::new(Box::new([]))));
+            return Ok(Self::default());
         }
 
         let mut quotes = Vec::new();
         loop {
             let location = input.current_source_location();
             let opening = match input.next() {
-                Ok(&Token::QuotedString(ref value)) => value.as_ref().to_owned().into_boxed_str(),
+                Ok(&Token::QuotedString(ref value)) => value.as_ref().to_owned().into(),
                 Ok(t) => return Err(location.new_unexpected_token_error(t.clone())),
                 Err(_) => break,
             };
 
-            let closing = input.expect_string()?.as_ref().to_owned().into_boxed_str();
+            let closing = input.expect_string()?.as_ref().to_owned().into();
             quotes.push(QuotePair { opening, closing });
         }
 
         if !quotes.is_empty() {
-            Ok(Quotes(Arc::new(quotes.into_boxed_slice())))
+            Ok(Quotes(crate::ArcSlice::from_iter(quotes.into_iter())))
         } else {
             Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError))
         }
diff --git a/components/style/values/specified/mod.rs b/components/style/values/specified/mod.rs
index 83fc71444bb..409f5abe161 100644
--- a/components/style/values/specified/mod.rs
+++ b/components/style/values/specified/mod.rs
@@ -54,8 +54,6 @@ pub use self::font::{FontSize, FontSizeAdjust, FontStretch, FontSynthesis};
 pub use self::font::{FontVariantAlternates, FontWeight};
 pub use self::font::{FontVariantEastAsian, FontVariationSettings};
 pub use self::font::{MozScriptLevel, MozScriptMinSize, MozScriptSizeMultiplier, XLang, XTextZoom};
-#[cfg(feature = "gecko")]
-pub use self::gecko::ScrollSnapPoint;
 pub use self::image::{ColorStop, EndingShape as GradientEndingShape, Gradient};
 pub use self::image::{GradientItem, GradientKind, Image, ImageLayer, MozImageRect};
 pub use self::length::{AbsoluteLength, CalcLengthPercentage, CharacterWidth};
@@ -68,7 +66,7 @@ pub use self::length::{NonNegativeLengthPercentage, NonNegativeLengthPercentageO
 pub use self::list::ListStyleType;
 pub use self::list::MozListReversed;
 pub use self::list::{QuotePair, Quotes};
-pub use self::motion::OffsetPath;
+pub use self::motion::{OffsetPath, OffsetRotate};
 pub use self::outline::OutlineStyle;
 pub use self::percentage::Percentage;
 pub use self::position::{GridAutoFlow, GridTemplateAreas, Position};
@@ -81,7 +79,7 @@ pub use self::svg::{SVGPaintOrder, SVGStrokeDashArray, SVGWidth};
 pub use self::svg_path::SVGPathData;
 pub use self::table::XSpan;
 pub use self::text::TextTransform;
-pub use self::text::{InitialLetter, LetterSpacing, LineHeight, TextAlign};
+pub use self::text::{InitialLetter, LetterSpacing, LineBreak, LineHeight, TextAlign};
 pub use self::text::{OverflowWrap, TextEmphasisPosition, TextEmphasisStyle, WordBreak};
 pub use self::text::{TextAlignKeyword, TextDecorationLine, TextOverflow, WordSpacing};
 pub use self::time::Time;
diff --git a/components/style/values/specified/motion.rs b/components/style/values/specified/motion.rs
index 7d72796397e..97609ea20b0 100644
--- a/components/style/values/specified/motion.rs
+++ b/components/style/values/specified/motion.rs
@@ -5,13 +5,17 @@
 //! Specified types for CSS values that are related to motion path.
 
 use crate::parser::{Parse, ParserContext};
-use crate::values::specified::SVGPathData;
+use crate::values::computed::motion::OffsetRotate as ComputedOffsetRotate;
+use crate::values::computed::{Context, ToComputedValue};
+use crate::values::specified::{Angle, SVGPathData};
+use crate::Zero;
 use cssparser::Parser;
 use style_traits::{ParseError, StyleParseErrorKind};
 
 /// The offset-path value.
 ///
 /// https://drafts.fxtf.org/motion-1/#offset-path-property
+/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(
     Animate,
     Clone,
@@ -26,6 +30,7 @@ use style_traits::{ParseError, StyleParseErrorKind};
     ToResolvedValue,
     ToShmem,
 )]
+#[repr(C, u8)]
 pub enum OffsetPath {
     // We could merge SVGPathData into ShapeSource, so we could reuse them. However,
     // we don't want to support other value for offset-path, so use SVGPathData only for now.
@@ -73,3 +78,104 @@ impl Parse for OffsetPath {
         })
     }
 }
+
+/// The direction of offset-rotate.
+#[derive(Clone, Copy, Debug, MallocSizeOf, Parse, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
+#[repr(u8)]
+pub enum OffsetRotateDirection {
+    /// Unspecified direction keyword.
+    #[css(skip)]
+    None,
+    /// 0deg offset (face forward).
+    Auto,
+    /// 180deg offset (face backward).
+    Reverse,
+}
+
+impl OffsetRotateDirection {
+    /// Returns true if it is none (i.e. the keyword is not specified).
+    #[inline]
+    fn is_none(&self) -> bool {
+        *self == OffsetRotateDirection::None
+    }
+}
+
+#[inline]
+fn direction_specified_and_angle_is_zero(direction: &OffsetRotateDirection, angle: &Angle) -> bool {
+    !direction.is_none() && angle.is_zero()
+}
+
+/// The specified offset-rotate.
+/// The syntax is: "[ auto | reverse ] || <angle>"
+///
+/// https://drafts.fxtf.org/motion-1/#offset-rotate-property
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
+pub struct OffsetRotate {
+    /// [auto | reverse].
+    #[css(skip_if = "OffsetRotateDirection::is_none")]
+    direction: OffsetRotateDirection,
+    /// <angle>.
+    /// If direction is None, this is a fixed angle which indicates a
+    /// constant clockwise rotation transformation applied to it by this
+    /// specified rotation angle. Otherwise, the angle will be added to
+    /// the angle of the direction in layout.
+    #[css(contextual_skip_if = "direction_specified_and_angle_is_zero")]
+    angle: Angle,
+}
+
+impl Parse for OffsetRotate {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        let location = input.current_source_location();
+        let mut direction = input.try(OffsetRotateDirection::parse);
+        let angle = input.try(|i| Angle::parse(context, i));
+        if direction.is_err() {
+            // The direction and angle could be any order, so give it a change to parse
+            // direction again.
+            direction = input.try(OffsetRotateDirection::parse);
+        }
+
+        if direction.is_err() && angle.is_err() {
+            return Err(location.new_custom_error(StyleParseErrorKind::UnspecifiedError));
+        }
+
+        Ok(OffsetRotate {
+            direction: direction.unwrap_or(OffsetRotateDirection::None),
+            angle: angle.unwrap_or(Zero::zero()),
+        })
+    }
+}
+
+impl ToComputedValue for OffsetRotate {
+    type ComputedValue = ComputedOffsetRotate;
+
+    #[inline]
+    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
+        use crate::values::computed::Angle as ComputedAngle;
+
+        ComputedOffsetRotate {
+            auto: !self.direction.is_none(),
+            angle: if self.direction == OffsetRotateDirection::Reverse {
+                // The computed value should always convert "reverse" into "auto".
+                // e.g. "reverse calc(20deg + 10deg)" => "auto 210deg"
+                self.angle.to_computed_value(context) + ComputedAngle::from_degrees(180.0)
+            } else {
+                self.angle.to_computed_value(context)
+            },
+        }
+    }
+
+    #[inline]
+    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
+        OffsetRotate {
+            direction: if computed.auto {
+                OffsetRotateDirection::Auto
+            } else {
+                OffsetRotateDirection::None
+            },
+            angle: ToComputedValue::from_computed_value(&computed.angle),
+        }
+    }
+}
diff --git a/components/style/values/specified/svg.rs b/components/style/values/specified/svg.rs
index dd4990782a0..578870a4a91 100644
--- a/components/style/values/specified/svg.rs
+++ b/components/style/values/specified/svg.rs
@@ -12,7 +12,7 @@ use crate::values::specified::AllowQuirks;
 use crate::values::specified::LengthPercentage;
 use crate::values::specified::{NonNegativeLengthPercentage, Opacity};
 use crate::values::CustomIdent;
-use cssparser::Parser;
+use cssparser::{Parser, Token};
 use std::fmt::{self, Write};
 use style_traits::{CommaWithSpace, CssWriter, ParseError, Separator};
 use style_traits::{StyleParseErrorKind, ToCss};
@@ -243,11 +243,28 @@ impl ToCss for SVGPaintOrder {
     }
 }
 
+bitflags! {
+    /// The context properties we understand.
+    #[derive(Default, MallocSizeOf, SpecifiedValueInfo, ToComputedValue, ToResolvedValue, ToShmem)]
+    #[repr(C)]
+    pub struct ContextPropertyBits: u8 {
+        /// `fill`
+        const FILL = 1 << 0;
+        /// `stroke`
+        const STROKE = 1 << 1;
+        /// `fill-opacity`
+        const FILL_OPACITY = 1 << 2;
+        /// `stroke-opacity`
+        const STROKE_OPACITY = 1 << 3;
+    }
+}
+
 /// Specified MozContextProperties value.
 /// Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/-moz-context-properties)
 #[derive(
     Clone,
     Debug,
+    Default,
     MallocSizeOf,
     PartialEq,
     SpecifiedValueInfo,
@@ -256,19 +273,61 @@ impl ToCss for SVGPaintOrder {
     ToResolvedValue,
     ToShmem,
 )]
-pub struct MozContextProperties(pub CustomIdent);
+#[repr(C)]
+pub struct MozContextProperties {
+    #[css(iterable, if_empty = "none")]
+    #[ignore_malloc_size_of = "Arc"]
+    idents: crate::ArcSlice<CustomIdent>,
+    #[css(skip)]
+    bits: ContextPropertyBits,
+}
 
 impl Parse for MozContextProperties {
     fn parse<'i, 't>(
         _context: &ParserContext,
         input: &mut Parser<'i, 't>,
     ) -> Result<MozContextProperties, ParseError<'i>> {
-        let location = input.current_source_location();
-        let i = input.expect_ident()?;
-        Ok(MozContextProperties(CustomIdent::from_ident(
-            location,
-            i,
-            &["all", "none", "auto"],
-        )?))
+        let mut values = vec![];
+        let mut bits = ContextPropertyBits::empty();
+        loop {
+            {
+                let location = input.current_source_location();
+                let ident = input.expect_ident()?;
+
+                if ident.eq_ignore_ascii_case("none") && values.is_empty() {
+                    return Ok(Self::default());
+                }
+
+                let ident = CustomIdent::from_ident(location, ident, &["all", "none", "auto"])?;
+
+                if ident.0 == atom!("fill") {
+                    bits.insert(ContextPropertyBits::FILL);
+                } else if ident.0 == atom!("stroke") {
+                    bits.insert(ContextPropertyBits::STROKE);
+                } else if ident.0 == atom!("fill-opacity") {
+                    bits.insert(ContextPropertyBits::FILL_OPACITY);
+                } else if ident.0 == atom!("stroke-opacity") {
+                    bits.insert(ContextPropertyBits::STROKE_OPACITY);
+                }
+
+                values.push(ident);
+            }
+
+            let location = input.current_source_location();
+            match input.next() {
+                Ok(&Token::Comma) => continue,
+                Err(..) => break,
+                Ok(other) => return Err(location.new_unexpected_token_error(other.clone())),
+            }
+        }
+
+        if values.is_empty() {
+            return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
+        }
+
+        Ok(MozContextProperties {
+            idents: crate::ArcSlice::from_iter(values.into_iter()),
+            bits,
+        })
     }
 }
diff --git a/components/style/values/specified/text.rs b/components/style/values/specified/text.rs
index 6be20f58618..188eb18f720 100644
--- a/components/style/values/specified/text.rs
+++ b/components/style/values/specified/text.rs
@@ -134,14 +134,16 @@ impl ToComputedValue for LineHeight {
 }
 
 /// A generic value for the `text-overflow` property.
+/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(Clone, Debug, Eq, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
+#[repr(C, u8)]
 pub enum TextOverflowSide {
     /// Clip inline content.
     Clip,
     /// Render ellipsis to represent clipped inline content.
     Ellipsis,
     /// Render a given string to represent clipped inline content.
-    String(Box<str>),
+    String(crate::OwnedStr),
 }
 
 impl Parse for TextOverflowSide {
@@ -160,9 +162,9 @@ impl Parse for TextOverflowSide {
                     ))
                 }
             },
-            Token::QuotedString(ref v) => Ok(TextOverflowSide::String(
-                v.as_ref().to_owned().into_boxed_str(),
-            )),
+            Token::QuotedString(ref v) => {
+                Ok(TextOverflowSide::String(v.as_ref().to_owned().into()))
+            },
             ref t => Err(location.new_unexpected_token_error(t.clone())),
         }
     }
@@ -1005,6 +1007,31 @@ pub enum WordBreak {
     BreakWord,
 }
 
+/// Values for the `line-break` property.
+#[repr(u8)]
+#[derive(
+    Clone,
+    Copy,
+    Debug,
+    Eq,
+    MallocSizeOf,
+    Parse,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[allow(missing_docs)]
+pub enum LineBreak {
+    Auto,
+    Loose,
+    Normal,
+    Strict,
+    Anywhere,
+}
+
 /// Values for the `overflow-wrap` property.
 #[repr(u8)]
 #[derive(
diff --git a/components/style/values/specified/transform.rs b/components/style/values/specified/transform.rs
index a4dc87d3217..e942cf13085 100644
--- a/components/style/values/specified/transform.rs
+++ b/components/style/values/specified/transform.rs
@@ -42,183 +42,187 @@ impl Transform {
             .try(|input| input.expect_ident_matching("none"))
             .is_ok()
         {
-            return Ok(generic::Transform(Vec::new()));
+            return Ok(generic::Transform::none());
         }
 
-        Ok(generic::Transform(Space::parse(input, |input| {
-            let function = input.expect_function()?.clone();
-            input.parse_nested_block(|input| {
-                let location = input.current_source_location();
-                let result = match_ignore_ascii_case! { &function,
-                    "matrix" => {
-                        let a = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let b = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let c = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let d = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        // Standard matrix parsing.
-                        let e = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let f = Number::parse(context, input)?;
-                        Ok(generic::TransformOperation::Matrix(Matrix { a, b, c, d, e, f }))
-                    },
-                    "matrix3d" => {
-                        let m11 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m12 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m13 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m14 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m21 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m22 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m23 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m24 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m31 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m32 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m33 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m34 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        // Standard matrix3d parsing.
-                        let m41 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m42 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m43 = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let m44 = Number::parse(context, input)?;
-                        Ok(generic::TransformOperation::Matrix3D(Matrix3D {
-                            m11, m12, m13, m14,
-                            m21, m22, m23, m24,
-                            m31, m32, m33, m34,
-                            m41, m42, m43, m44,
-                        }))
-                    },
-                    "translate" => {
-                        let sx = specified::LengthPercentage::parse(context, input)?;
-                        if input.try(|input| input.expect_comma()).is_ok() {
-                            let sy = specified::LengthPercentage::parse(context, input)?;
-                            Ok(generic::TransformOperation::Translate(sx, sy))
-                        } else {
-                            Ok(generic::TransformOperation::Translate(sx, Zero::zero()))
-                        }
-                    },
-                    "translatex" => {
-                        let tx = specified::LengthPercentage::parse(context, input)?;
-                        Ok(generic::TransformOperation::TranslateX(tx))
-                    },
-                    "translatey" => {
-                        let ty = specified::LengthPercentage::parse(context, input)?;
-                        Ok(generic::TransformOperation::TranslateY(ty))
-                    },
-                    "translatez" => {
-                        let tz = specified::Length::parse(context, input)?;
-                        Ok(generic::TransformOperation::TranslateZ(tz))
-                    },
-                    "translate3d" => {
-                        let tx = specified::LengthPercentage::parse(context, input)?;
-                        input.expect_comma()?;
-                        let ty = specified::LengthPercentage::parse(context, input)?;
-                        input.expect_comma()?;
-                        let tz = specified::Length::parse(context, input)?;
-                        Ok(generic::TransformOperation::Translate3D(tx, ty, tz))
-                    },
-                    "scale" => {
-                        let sx = Number::parse(context, input)?;
-                        if input.try(|input| input.expect_comma()).is_ok() {
+        Ok(generic::Transform(
+            Space::parse(input, |input| {
+                let function = input.expect_function()?.clone();
+                input.parse_nested_block(|input| {
+                    let location = input.current_source_location();
+                    let result = match_ignore_ascii_case! { &function,
+                        "matrix" => {
+                            let a = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let b = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let c = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let d = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            // Standard matrix parsing.
+                            let e = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let f = Number::parse(context, input)?;
+                            Ok(generic::TransformOperation::Matrix(Matrix { a, b, c, d, e, f }))
+                        },
+                        "matrix3d" => {
+                            let m11 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m12 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m13 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m14 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m21 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m22 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m23 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m24 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m31 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m32 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m33 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m34 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            // Standard matrix3d parsing.
+                            let m41 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m42 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m43 = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let m44 = Number::parse(context, input)?;
+                            Ok(generic::TransformOperation::Matrix3D(Matrix3D {
+                                m11, m12, m13, m14,
+                                m21, m22, m23, m24,
+                                m31, m32, m33, m34,
+                                m41, m42, m43, m44,
+                            }))
+                        },
+                        "translate" => {
+                            let sx = specified::LengthPercentage::parse(context, input)?;
+                            if input.try(|input| input.expect_comma()).is_ok() {
+                                let sy = specified::LengthPercentage::parse(context, input)?;
+                                Ok(generic::TransformOperation::Translate(sx, sy))
+                            } else {
+                                Ok(generic::TransformOperation::Translate(sx, Zero::zero()))
+                            }
+                        },
+                        "translatex" => {
+                            let tx = specified::LengthPercentage::parse(context, input)?;
+                            Ok(generic::TransformOperation::TranslateX(tx))
+                        },
+                        "translatey" => {
+                            let ty = specified::LengthPercentage::parse(context, input)?;
+                            Ok(generic::TransformOperation::TranslateY(ty))
+                        },
+                        "translatez" => {
+                            let tz = specified::Length::parse(context, input)?;
+                            Ok(generic::TransformOperation::TranslateZ(tz))
+                        },
+                        "translate3d" => {
+                            let tx = specified::LengthPercentage::parse(context, input)?;
+                            input.expect_comma()?;
+                            let ty = specified::LengthPercentage::parse(context, input)?;
+                            input.expect_comma()?;
+                            let tz = specified::Length::parse(context, input)?;
+                            Ok(generic::TransformOperation::Translate3D(tx, ty, tz))
+                        },
+                        "scale" => {
+                            let sx = Number::parse(context, input)?;
+                            if input.try(|input| input.expect_comma()).is_ok() {
+                                let sy = Number::parse(context, input)?;
+                                Ok(generic::TransformOperation::Scale(sx, sy))
+                            } else {
+                                Ok(generic::TransformOperation::Scale(sx, sx))
+                            }
+                        },
+                        "scalex" => {
+                            let sx = Number::parse(context, input)?;
+                            Ok(generic::TransformOperation::ScaleX(sx))
+                        },
+                        "scaley" => {
                             let sy = Number::parse(context, input)?;
-                            Ok(generic::TransformOperation::Scale(sx, sy))
-                        } else {
-                            Ok(generic::TransformOperation::Scale(sx, sx))
-                        }
-                    },
-                    "scalex" => {
-                        let sx = Number::parse(context, input)?;
-                        Ok(generic::TransformOperation::ScaleX(sx))
-                    },
-                    "scaley" => {
-                        let sy = Number::parse(context, input)?;
-                        Ok(generic::TransformOperation::ScaleY(sy))
-                    },
-                    "scalez" => {
-                        let sz = Number::parse(context, input)?;
-                        Ok(generic::TransformOperation::ScaleZ(sz))
-                    },
-                    "scale3d" => {
-                        let sx = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let sy = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let sz = Number::parse(context, input)?;
-                        Ok(generic::TransformOperation::Scale3D(sx, sy, sz))
-                    },
-                    "rotate" => {
-                        let theta = specified::Angle::parse_with_unitless(context, input)?;
-                        Ok(generic::TransformOperation::Rotate(theta))
-                    },
-                    "rotatex" => {
-                        let theta = specified::Angle::parse_with_unitless(context, input)?;
-                        Ok(generic::TransformOperation::RotateX(theta))
-                    },
-                    "rotatey" => {
-                        let theta = specified::Angle::parse_with_unitless(context, input)?;
-                        Ok(generic::TransformOperation::RotateY(theta))
-                    },
-                    "rotatez" => {
-                        let theta = specified::Angle::parse_with_unitless(context, input)?;
-                        Ok(generic::TransformOperation::RotateZ(theta))
-                    },
-                    "rotate3d" => {
-                        let ax = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let ay = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let az = Number::parse(context, input)?;
-                        input.expect_comma()?;
-                        let theta = specified::Angle::parse_with_unitless(context, input)?;
-                        // TODO(gw): Check that the axis can be normalized.
-                        Ok(generic::TransformOperation::Rotate3D(ax, ay, az, theta))
-                    },
-                    "skew" => {
-                        let ax = specified::Angle::parse_with_unitless(context, input)?;
-                        if input.try(|input| input.expect_comma()).is_ok() {
-                            let ay = specified::Angle::parse_with_unitless(context, input)?;
-                            Ok(generic::TransformOperation::Skew(ax, ay))
-                        } else {
-                            Ok(generic::TransformOperation::Skew(ax, Zero::zero()))
-                        }
-                    },
-                    "skewx" => {
-                        let theta = specified::Angle::parse_with_unitless(context, input)?;
-                        Ok(generic::TransformOperation::SkewX(theta))
-                    },
-                    "skewy" => {
-                        let theta = specified::Angle::parse_with_unitless(context, input)?;
-                        Ok(generic::TransformOperation::SkewY(theta))
-                    },
-                    "perspective" => {
-                        let d = specified::Length::parse_non_negative(context, input)?;
-                        Ok(generic::TransformOperation::Perspective(d))
-                    },
-                    _ => Err(()),
-                };
-                result.map_err(|()| {
-                    location
-                        .new_custom_error(StyleParseErrorKind::UnexpectedFunction(function.clone()))
+                            Ok(generic::TransformOperation::ScaleY(sy))
+                        },
+                        "scalez" => {
+                            let sz = Number::parse(context, input)?;
+                            Ok(generic::TransformOperation::ScaleZ(sz))
+                        },
+                        "scale3d" => {
+                            let sx = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let sy = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let sz = Number::parse(context, input)?;
+                            Ok(generic::TransformOperation::Scale3D(sx, sy, sz))
+                        },
+                        "rotate" => {
+                            let theta = specified::Angle::parse_with_unitless(context, input)?;
+                            Ok(generic::TransformOperation::Rotate(theta))
+                        },
+                        "rotatex" => {
+                            let theta = specified::Angle::parse_with_unitless(context, input)?;
+                            Ok(generic::TransformOperation::RotateX(theta))
+                        },
+                        "rotatey" => {
+                            let theta = specified::Angle::parse_with_unitless(context, input)?;
+                            Ok(generic::TransformOperation::RotateY(theta))
+                        },
+                        "rotatez" => {
+                            let theta = specified::Angle::parse_with_unitless(context, input)?;
+                            Ok(generic::TransformOperation::RotateZ(theta))
+                        },
+                        "rotate3d" => {
+                            let ax = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let ay = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let az = Number::parse(context, input)?;
+                            input.expect_comma()?;
+                            let theta = specified::Angle::parse_with_unitless(context, input)?;
+                            // TODO(gw): Check that the axis can be normalized.
+                            Ok(generic::TransformOperation::Rotate3D(ax, ay, az, theta))
+                        },
+                        "skew" => {
+                            let ax = specified::Angle::parse_with_unitless(context, input)?;
+                            if input.try(|input| input.expect_comma()).is_ok() {
+                                let ay = specified::Angle::parse_with_unitless(context, input)?;
+                                Ok(generic::TransformOperation::Skew(ax, ay))
+                            } else {
+                                Ok(generic::TransformOperation::Skew(ax, Zero::zero()))
+                            }
+                        },
+                        "skewx" => {
+                            let theta = specified::Angle::parse_with_unitless(context, input)?;
+                            Ok(generic::TransformOperation::SkewX(theta))
+                        },
+                        "skewy" => {
+                            let theta = specified::Angle::parse_with_unitless(context, input)?;
+                            Ok(generic::TransformOperation::SkewY(theta))
+                        },
+                        "perspective" => {
+                            let d = specified::Length::parse_non_negative(context, input)?;
+                            Ok(generic::TransformOperation::Perspective(d))
+                        },
+                        _ => Err(()),
+                    };
+                    result.map_err(|()| {
+                        location.new_custom_error(StyleParseErrorKind::UnexpectedFunction(
+                            function.clone(),
+                        ))
+                    })
                 })
-            })
-        })?))
+            })?
+            .into(),
+        ))
     }
 }
 
diff --git a/components/style_traits/Cargo.toml b/components/style_traits/Cargo.toml
index 846579d462c..acf46422861 100644
--- a/components/style_traits/Cargo.toml
+++ b/components/style_traits/Cargo.toml
@@ -18,6 +18,7 @@ app_units = "0.7"
 cssparser = "0.25"
 bitflags = "1.0"
 euclid = "0.19"
+lazy_static = "1"
 malloc_size_of = { path = "../malloc_size_of" }
 malloc_size_of_derive = "0.1"
 selectors = { path = "../selectors" }
diff --git a/components/style_traits/arc_slice.rs b/components/style_traits/arc_slice.rs
index dd1b99d3424..6a151e3dc5a 100644
--- a/components/style_traits/arc_slice.rs
+++ b/components/style_traits/arc_slice.rs
@@ -5,16 +5,19 @@
 //! A thin atomically-reference-counted slice.
 
 use servo_arc::ThinArc;
-use std::mem;
 use std::ops::Deref;
 use std::ptr::NonNull;
+use std::{iter, mem};
 
 /// A canary that we stash in ArcSlices.
 ///
 /// Given we cannot use a zero-sized-type for the header, since well, C++
 /// doesn't have zsts, and we want to use cbindgen for this type, we may as well
 /// assert some sanity at runtime.
-const ARC_SLICE_CANARY: u32 = 0xf3f3f3f3;
+///
+/// We use an u64, to guarantee that we can use a single singleton for every
+/// empty slice, even if the types they hold are aligned differently.
+const ARC_SLICE_CANARY: u64 = 0xf3f3f3f3f3f3f3f3;
 
 /// A wrapper type for a refcounted slice using ThinArc.
 ///
@@ -22,7 +25,7 @@ const ARC_SLICE_CANARY: u32 = 0xf3f3f3f3;
 /// cbindgen:derive-neq=false
 #[repr(C)]
 #[derive(Clone, Debug, Eq, PartialEq, ToShmem)]
-pub struct ArcSlice<T>(#[shmem(field_bound)] ThinArc<u32, T>);
+pub struct ArcSlice<T>(#[shmem(field_bound)] ThinArc<u64, T>);
 
 impl<T> Deref for ArcSlice<T> {
     type Target = [T];
@@ -34,12 +37,28 @@ impl<T> Deref for ArcSlice<T> {
     }
 }
 
-/// The inner pointer of an ArcSlice<T>, to be sent via FFI.
-/// The type of the pointer is a bit of a lie, we just want to preserve the type
-/// but these pointers cannot be constructed outside of this crate, so we're
-/// good.
-#[repr(C)]
-pub struct ForgottenArcSlicePtr<T>(NonNull<T>);
+lazy_static! {
+    // ThinArc doesn't support alignments greater than align_of::<u64>.
+    static ref EMPTY_ARC_SLICE: ArcSlice<u64> = {
+        ArcSlice(ThinArc::from_header_and_iter(ARC_SLICE_CANARY, iter::empty()))
+    };
+}
+
+impl<T> Default for ArcSlice<T> {
+    #[allow(unsafe_code)]
+    fn default() -> Self {
+        debug_assert!(
+            mem::align_of::<T>() <= mem::align_of::<u64>(),
+            "Need to increase the alignment of EMPTY_ARC_SLICE"
+        );
+        unsafe {
+            let empty: ArcSlice<_> = EMPTY_ARC_SLICE.clone();
+            let empty: Self = mem::transmute(empty);
+            debug_assert_eq!(empty.len(), 0);
+            empty
+        }
+    }
+}
 
 impl<T> ArcSlice<T> {
     /// Creates an Arc for a slice using the given iterator to generate the
@@ -49,6 +68,9 @@ impl<T> ArcSlice<T> {
     where
         I: Iterator<Item = T> + ExactSizeIterator,
     {
+        if items.len() == 0 {
+            return Self::default();
+        }
         ArcSlice(ThinArc::from_header_and_iter(ARC_SLICE_CANARY, items))
     }
 
@@ -63,4 +85,21 @@ impl<T> ArcSlice<T> {
         mem::forget(self);
         ret
     }
+
+    /// Leaks an empty arc slice pointer, and returns it. Only to be used to
+    /// construct ArcSlices from FFI.
+    #[inline]
+    pub fn leaked_empty_ptr() -> *mut std::os::raw::c_void {
+        let empty: ArcSlice<_> = EMPTY_ARC_SLICE.clone();
+        let ptr = empty.0.ptr();
+        std::mem::forget(empty);
+        ptr as *mut _
+    }
 }
+
+/// The inner pointer of an ArcSlice<T>, to be sent via FFI.
+/// The type of the pointer is a bit of a lie, we just want to preserve the type
+/// but these pointers cannot be constructed outside of this crate, so we're
+/// good.
+#[repr(C)]
+pub struct ForgottenArcSlicePtr<T>(NonNull<T>);
diff --git a/components/style_traits/lib.rs b/components/style_traits/lib.rs
index d4a907fa956..4e89f6fdf67 100644
--- a/components/style_traits/lib.rs
+++ b/components/style_traits/lib.rs
@@ -16,6 +16,8 @@ extern crate bitflags;
 #[macro_use]
 extern crate cssparser;
 extern crate euclid;
+#[macro_use]
+extern crate lazy_static;
 extern crate malloc_size_of;
 #[macro_use]
 extern crate malloc_size_of_derive;
@@ -91,6 +93,7 @@ pub mod values;
 #[macro_use]
 pub mod viewport;
 pub mod owned_slice;
+pub mod owned_str;
 
 pub use crate::specified_value_info::{CssType, KeywordsCollectFn, SpecifiedValueInfo};
 pub use crate::values::{
@@ -149,8 +152,6 @@ pub enum StyleParseErrorKind<'i> {
 
     /// The property declaration was for an unknown property.
     UnknownProperty(CowRcStr<'i>),
-    /// An unknown vendor-specific identifier was encountered.
-    UnknownVendorProperty,
     /// The property declaration was for a disabled experimental property.
     ExperimentalProperty,
     /// The property declaration contained an invalid color value.
diff --git a/components/style_traits/owned_slice.rs b/components/style_traits/owned_slice.rs
index f2b0de4a4a0..33d3ac1c2ab 100644
--- a/components/style_traits/owned_slice.rs
+++ b/components/style_traits/owned_slice.rs
@@ -10,7 +10,7 @@ use malloc_size_of::{MallocShallowSizeOf, MallocSizeOf, MallocSizeOfOps};
 use std::marker::PhantomData;
 use std::ops::{Deref, DerefMut};
 use std::ptr::NonNull;
-use std::{fmt, mem, slice};
+use std::{fmt, iter, mem, slice};
 use to_shmem::{SharedMemoryBuilder, ToShmem};
 
 /// A struct that basically replaces a `Box<[T]>`, but which cbindgen can
@@ -93,7 +93,7 @@ impl<T: Sized> OwnedSlice<T> {
 
     /// Iterate over all the elements in the slice taking ownership of them.
     #[inline]
-    pub fn into_iter(self) -> impl Iterator<Item = T> {
+    pub fn into_iter(self) -> impl Iterator<Item = T> + ExactSizeIterator {
         self.into_vec().into_iter()
     }
 
@@ -164,3 +164,10 @@ impl<T: ToShmem + Sized> ToShmem for OwnedSlice<T> {
         }
     }
 }
+
+impl<T> iter::FromIterator<T> for OwnedSlice<T> {
+    #[inline]
+    fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
+        Vec::from_iter(iter).into()
+    }
+}
diff --git a/components/style_traits/owned_str.rs b/components/style_traits/owned_str.rs
new file mode 100644
index 00000000000..42a83a07713
--- /dev/null
+++ b/components/style_traits/owned_str.rs
@@ -0,0 +1,53 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#![allow(unsafe_code)]
+
+//! A replacement for `Box<str>` that has a defined layout for FFI.
+
+use crate::owned_slice::OwnedSlice;
+use std::fmt;
+use std::ops::{Deref, DerefMut};
+
+/// A struct that basically replaces a Box<str>, but with a defined layout,
+/// suitable for FFI.
+#[repr(C)]
+#[derive(Clone, Default, Eq, MallocSizeOf, PartialEq, ToShmem)]
+pub struct OwnedStr(OwnedSlice<u8>);
+
+impl fmt::Debug for OwnedStr {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.deref().fmt(formatter)
+    }
+}
+
+impl Deref for OwnedStr {
+    type Target = str;
+
+    #[inline(always)]
+    fn deref(&self) -> &Self::Target {
+        unsafe { std::str::from_utf8_unchecked(&*self.0) }
+    }
+}
+
+impl DerefMut for OwnedStr {
+    #[inline(always)]
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        unsafe { std::str::from_utf8_unchecked_mut(&mut *self.0) }
+    }
+}
+
+impl From<Box<str>> for OwnedStr {
+    #[inline]
+    fn from(b: Box<str>) -> Self {
+        Self::from(b.into_string())
+    }
+}
+
+impl From<String> for OwnedStr {
+    #[inline]
+    fn from(s: String) -> Self {
+        OwnedStr(s.into_bytes().into())
+    }
+}
diff --git a/components/style_traits/specified_value_info.rs b/components/style_traits/specified_value_info.rs
index 63a7b71d990..5aaf64ac955 100644
--- a/components/style_traits/specified_value_info.rs
+++ b/components/style_traits/specified_value_info.rs
@@ -5,6 +5,7 @@
 //! Value information for devtools.
 
 use crate::arc_slice::ArcSlice;
+use crate::owned_slice::OwnedSlice;
 use servo_arc::Arc;
 use std::ops::Range;
 use std::sync::Arc as StdArc;
@@ -83,6 +84,7 @@ impl SpecifiedValueInfo for u16 {}
 impl SpecifiedValueInfo for u32 {}
 impl SpecifiedValueInfo for str {}
 impl SpecifiedValueInfo for String {}
+impl SpecifiedValueInfo for crate::owned_str::OwnedStr {}
 
 #[cfg(feature = "servo")]
 impl SpecifiedValueInfo for ::servo_atoms::Atom {}
@@ -114,6 +116,7 @@ macro_rules! impl_generic_specified_value_info {
     };
 }
 impl_generic_specified_value_info!(Option<T>);
+impl_generic_specified_value_info!(OwnedSlice<T>);
 impl_generic_specified_value_info!(Vec<T>);
 impl_generic_specified_value_info!(Arc<T>);
 impl_generic_specified_value_info!(StdArc<T>);
diff --git a/components/style_traits/values.rs b/components/style_traits/values.rs
index 5c3f3ab255d..0c3166858a2 100644
--- a/components/style_traits/values.rs
+++ b/components/style_traits/values.rs
@@ -75,6 +75,16 @@ where
     }
 }
 
+impl ToCss for crate::owned_str::OwnedStr {
+    #[inline]
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        serialize_string(self, dest)
+    }
+}
+
 impl ToCss for str {
     #[inline]
     fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
diff --git a/tests/unit/style/animated_properties.rs b/tests/unit/style/animated_properties.rs
index dd233f01b89..fd03a1904e8 100644
--- a/tests/unit/style/animated_properties.rs
+++ b/tests/unit/style/animated_properties.rs
@@ -4,7 +4,6 @@
 
 use cssparser::RGBA;
 use style::values::animated::{Animate, Procedure, ToAnimatedValue};
-use style::values::generics::transform::{Transform, TransformOperation};
 
 fn interpolate_rgba(from: RGBA, to: RGBA, progress: f64) -> RGBA {
     let from = from.to_animated_value();
@@ -81,14 +80,3 @@ fn test_rgba_color_interepolation_out_of_range_clamped_2() {
         RGBA::from_floats(0.0, 0.0, 0.0, 0.0)
     );
 }
-
-#[test]
-fn test_transform_interpolation_on_scale() {
-    let from = Transform(vec![TransformOperation::Scale3D(1.0, 2.0, 1.0)]);
-    let to = Transform(vec![TransformOperation::Scale3D(2.0, 4.0, 2.0)]);
-    assert_eq!(
-        from.animate(&to, Procedure::Interpolate { progress: 0.5 })
-            .unwrap(),
-        Transform(vec![TransformOperation::Scale3D(1.5, 3.0, 1.5)])
-    );
-}
diff --git a/tests/unit/style/parsing/animation.rs b/tests/unit/style/parsing/animation.rs
deleted file mode 100644
index f67d77e9afd..00000000000
--- a/tests/unit/style/parsing/animation.rs
+++ /dev/null
@@ -1,43 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-use crate::parsing::parse;
-use servo_atoms::Atom;
-use style::parser::Parse;
-use style::properties::longhands::animation_name;
-use style::values::specified::AnimationIterationCount;
-use style::values::{CustomIdent, KeyframesName};
-use style_traits::ToCss;
-
-#[test]
-fn test_animation_name() {
-    use self::animation_name::single_value::SpecifiedValue as SingleValue;
-    let other_name = Atom::from("other-name");
-    assert_eq!(
-        parse_longhand!(animation_name, "none"),
-        animation_name::SpecifiedValue(vec![SingleValue(None)])
-    );
-    assert_eq!(
-        parse_longhand!(
-            animation_name,
-            "other-name, none, 'other-name', \"other-name\""
-        ),
-        animation_name::SpecifiedValue(vec![
-            SingleValue(Some(KeyframesName::Ident(CustomIdent(other_name.clone())))),
-            SingleValue(None),
-            SingleValue(Some(KeyframesName::QuotedString(other_name.clone()))),
-            SingleValue(Some(KeyframesName::QuotedString(other_name.clone())))
-        ])
-    );
-}
-
-#[test]
-fn test_animation_iteration() {
-    assert_roundtrip_with_context!(AnimationIterationCount::parse, "0", "0");
-    assert_roundtrip_with_context!(AnimationIterationCount::parse, "0.1", "0.1");
-    assert_roundtrip_with_context!(AnimationIterationCount::parse, "infinite", "infinite");
-
-    // Negative numbers are invalid
-    assert!(parse(AnimationIterationCount::parse, "-1").is_err());
-}
diff --git a/tests/unit/style/parsing/mod.rs b/tests/unit/style/parsing/mod.rs
index 095f74c9603..aff8d1fc47c 100644
--- a/tests/unit/style/parsing/mod.rs
+++ b/tests/unit/style/parsing/mod.rs
@@ -133,7 +133,6 @@ macro_rules! parse_longhand {
     };
 }
 
-mod animation;
 mod background;
 mod border;
 mod box_;
diff --git a/tests/unit/style/stylesheets.rs b/tests/unit/style/stylesheets.rs
index fe8a7b84269..c6b02f37eda 100644
--- a/tests/unit/style/stylesheets.rs
+++ b/tests/unit/style/stylesheets.rs
@@ -194,7 +194,7 @@ fn test_parse_stylesheet() {
                                 PropertyDeclaration::BackgroundPositionX(
                                     longhands::background_position_x::SpecifiedValue(vec![
                                         PositionComponent::zero(),
-                                    ]),
+                                    ].into()),
                                 ),
                                 Importance::Normal,
                             ),
@@ -202,7 +202,7 @@ fn test_parse_stylesheet() {
                                 PropertyDeclaration::BackgroundPositionY(
                                     longhands::background_position_y::SpecifiedValue(vec![
                                         PositionComponent::zero(),
-                                    ]),
+                                    ].into()),
                                 ),
                                 Importance::Normal,
                             ),
@@ -210,7 +210,7 @@ fn test_parse_stylesheet() {
                                 PropertyDeclaration::BackgroundRepeat(
                                     longhands::background_repeat::SpecifiedValue(
                                         vec![longhands::background_repeat::single_value
-                                                       ::get_initial_specified_value()],
+                                                       ::get_initial_specified_value()].into(),
                                     ),
                                 ),
                                 Importance::Normal,
@@ -219,7 +219,7 @@ fn test_parse_stylesheet() {
                                 PropertyDeclaration::BackgroundAttachment(
                                     longhands::background_attachment::SpecifiedValue(
                                         vec![longhands::background_attachment::single_value
-                                                       ::get_initial_specified_value()],
+                                                       ::get_initial_specified_value()].into(),
                                     ),
                                 ),
                                 Importance::Normal,
@@ -228,7 +228,7 @@ fn test_parse_stylesheet() {
                                 PropertyDeclaration::BackgroundImage(
                                     longhands::background_image::SpecifiedValue(
                                         vec![longhands::background_image::single_value
-                                                       ::get_initial_specified_value()],
+                                                       ::get_initial_specified_value()].into(),
                                     ),
                                 ),
                                 Importance::Normal,
@@ -237,7 +237,7 @@ fn test_parse_stylesheet() {
                                 PropertyDeclaration::BackgroundSize(
                                     longhands::background_size::SpecifiedValue(
                                         vec![longhands::background_size::single_value
-                                                       ::get_initial_specified_value()],
+                                                       ::get_initial_specified_value()].into(),
                                     ),
                                 ),
                                 Importance::Normal,
@@ -246,7 +246,7 @@ fn test_parse_stylesheet() {
                                 PropertyDeclaration::BackgroundOrigin(
                                     longhands::background_origin::SpecifiedValue(
                                         vec![longhands::background_origin::single_value
-                                                       ::get_initial_specified_value()],
+                                                       ::get_initial_specified_value()].into(),
                                     ),
                                 ),
                                 Importance::Normal,
@@ -255,7 +255,7 @@ fn test_parse_stylesheet() {
                                 PropertyDeclaration::BackgroundClip(
                                     longhands::background_clip::SpecifiedValue(
                                         vec![longhands::background_clip::single_value
-                                                       ::get_initial_specified_value()],
+                                                       ::get_initial_specified_value()].into(),
                                     ),
                                 ),
                                 Importance::Normal,
diff --git a/tests/wpt/metadata/css/filter-effects/filters-test-brightness-003.html.ini b/tests/wpt/metadata/css/filter-effects/filters-test-brightness-003.html.ini
deleted file mode 100644
index df5382158af..00000000000
--- a/tests/wpt/metadata/css/filter-effects/filters-test-brightness-003.html.ini
+++ /dev/null
@@ -1,2 +0,0 @@
-[filters-test-brightness-003.html]
-  expected: FAIL
diff --git a/tests/wpt/metadata/css/filter-effects/parsing/filter-computed.html.ini b/tests/wpt/metadata/css/filter-effects/parsing/filter-computed.html.ini
index 5ba47d10857..9b57d470e5b 100644
--- a/tests/wpt/metadata/css/filter-effects/parsing/filter-computed.html.ini
+++ b/tests/wpt/metadata/css/filter-effects/parsing/filter-computed.html.ini
@@ -2,42 +2,15 @@
   [Property filter value 'brightness()' computes to 'brightness(0)']
     expected: FAIL
 
-  [Property filter value 'sepia()' computes to 'sepia(1)']
-    expected: FAIL
-
-  [Property filter value 'saturate()' computes to 'saturate(1)']
-    expected: FAIL
-
-  [Property filter value 'grayscale()' computes to 'grayscale(1)']
-    expected: FAIL
-
   [Property filter value 'invert()' computes to 'invert(0)']
     expected: FAIL
 
-  [Property filter value 'hue-rotate()' computes to 'hue-rotate(0deg)']
-    expected: FAIL
-
   [Property filter value 'drop-shadow(1px 2px)' computes to 'drop-shadow(rgb(0, 255, 0) 1px 2px 0px)']
     expected: FAIL
 
-  [Property filter value 'blur()' computes to 'blur(0px)']
-    expected: FAIL
-
   [Property filter value 'drop-shadow(rgb(4, 5, 6) 1px 2px 0px)' computes to 'drop-shadow(rgb(4, 5, 6) 1px 2px 0px)']
     expected: FAIL
 
   [Property filter value 'blur(10px) url("https://www.example.com/picture.svg#f") contrast(20) brightness(30)' computes to 'blur(10px) url("https://www.example.com/picture.svg#f") contrast(20) brightness(30)']
     expected: FAIL
 
-  [Property filter value 'opacity()' computes to 'opacity(1)']
-    expected: FAIL
-
-  [Property filter value 'contrast()' computes to 'contrast(1)']
-    expected: FAIL
-
-  [Property filter value 'brightness()' computes to 'brightness(1)']
-    expected: FAIL
-
-  [Property filter value 'invert()' computes to 'invert(1)']
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/filter-effects/parsing/filter-parsing-valid.html.ini b/tests/wpt/metadata/css/filter-effects/parsing/filter-parsing-valid.html.ini
index 274ce737462..b8ca47ff7b3 100644
--- a/tests/wpt/metadata/css/filter-effects/parsing/filter-parsing-valid.html.ini
+++ b/tests/wpt/metadata/css/filter-effects/parsing/filter-parsing-valid.html.ini
@@ -59,30 +59,3 @@
   [Serialization should round-trip after setting e.style['filter'\] = "drop-shadow(rgba(4, 5, 6, 0.75) 1px 2px 3px)"]
     expected: FAIL
 
-  [e.style['filter'\] = "saturate()" should set the property value]
-    expected: FAIL
-
-  [e.style['filter'\] = "grayscale()" should set the property value]
-    expected: FAIL
-
-  [e.style['filter'\] = "sepia()" should set the property value]
-    expected: FAIL
-
-  [e.style['filter'\] = "blur()" should set the property value]
-    expected: FAIL
-
-  [e.style['filter'\] = "contrast()" should set the property value]
-    expected: FAIL
-
-  [e.style['filter'\] = "invert()" should set the property value]
-    expected: FAIL
-
-  [e.style['filter'\] = "brightness()" should set the property value]
-    expected: FAIL
-
-  [e.style['filter'\] = "opacity()" should set the property value]
-    expected: FAIL
-
-  [e.style['filter'\] = "hue-rotate()" should set the property value]
-    expected: FAIL
-