Auto merge of #17209 - servo:derive-all-the-things, r=emilio

Introduce more generics and more deriving

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13 files changed, 82 insertions, 188 deletions

diff --git a/components/style/values/computed/mod.rs b/components/style/values/computed/mod.rs
index 1fbaa17c87f..1547cf29424 100644
--- a/components/style/values/computed/mod.rs
+++ b/components/style/values/computed/mod.rs
@@ -42,7 +42,7 @@ pub use self::length::{CalcLengthOrPercentage, Length, LengthOrNumber, LengthOrP
 pub use self::length::{LengthOrPercentageOrAutoOrContent, LengthOrPercentageOrNone, LengthOrNone};
 pub use self::length::{MaxLength, MozLength};
 pub use self::position::Position;
-pub use self::text::{LetterSpacing, LineHeight, WordSpacing};
+pub use self::text::{InitialLetter, LetterSpacing, LineHeight, WordSpacing};
 pub use self::transform::{TimingFunction, TransformOrigin};
 
 pub mod background;
diff --git a/components/style/values/computed/text.rs b/components/style/values/computed/text.rs
index d45242015c4..857a985d851 100644
--- a/components/style/values/computed/text.rs
+++ b/components/style/values/computed/text.rs
@@ -6,9 +6,14 @@
 
 use app_units::Au;
 use properties::animated_properties::Animatable;
-use values::CSSFloat;
+use values::{CSSInteger, CSSFloat};
 use values::computed::length::{Length, LengthOrPercentage};
-use values::generics::text::{LineHeight as GenericLineHeight, Spacing};
+use values::generics::text::InitialLetter as GenericInitialLetter;
+use values::generics::text::LineHeight as GenericLineHeight;
+use values::generics::text::Spacing;
+
+/// A computed value for the `initial-letter` property.
+pub type InitialLetter = GenericInitialLetter<CSSFloat, CSSInteger>;
 
 /// A computed value for the `letter-spacing` property.
 pub type LetterSpacing = Spacing<Length>;
diff --git a/components/style/values/generics/background.rs b/components/style/values/generics/background.rs
index af8cef23a38..aa24454ef6d 100644
--- a/components/style/values/generics/background.rs
+++ b/components/style/values/generics/background.rs
@@ -4,11 +4,8 @@
 
 //! Generic types for CSS values related to backgrounds.
 
-use std::fmt;
-use style_traits::ToCss;
-
 /// A generic value for the `background-size` property.
-#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToComputedValue)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToComputedValue, ToCss)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum BackgroundSize<LengthOrPercentageOrAuto> {
     /// `<width> <height>`
@@ -32,21 +29,3 @@ impl<L> From<L> for BackgroundSize<L>
         BackgroundSize::Explicit { width: value.clone(), height: value }
     }
 }
-
-impl<L> ToCss for BackgroundSize<L>
-    where L: ToCss
-{
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
-        where W: fmt::Write
-    {
-        match *self {
-            BackgroundSize::Explicit { ref width, ref height } => {
-                width.to_css(dest)?;
-                dest.write_str(" ")?;
-                height.to_css(dest)
-            },
-            BackgroundSize::Cover => dest.write_str("cover"),
-            BackgroundSize::Contain => dest.write_str("contain"),
-        }
-    }
-}
diff --git a/components/style/values/generics/basic_shape.rs b/components/style/values/generics/basic_shape.rs
index b2d402dd38f..cd8e315f3b3 100644
--- a/components/style/values/generics/basic_shape.rs
+++ b/components/style/values/generics/basic_shape.rs
@@ -19,7 +19,7 @@ pub type ClippingShape<BasicShape> = ShapeSource<BasicShape, GeometryBox>;
 /// https://drafts.fxtf.org/css-masking-1/#typedef-geometry-box
 #[allow(missing_docs)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-#[derive(Clone, Copy, Debug, PartialEq)]
+#[derive(Clone, Copy, Debug, PartialEq, ToCss)]
 pub enum GeometryBox {
     FillBox,
     StrokeBox,
@@ -142,17 +142,6 @@ impl<B: ToCss, T: ToCss> ToCss for ShapeSource<B, T> {
     }
 }
 
-impl ToCss for GeometryBox {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-        match *self {
-            GeometryBox::FillBox => dest.write_str("fill-box"),
-            GeometryBox::StrokeBox => dest.write_str("stroke-box"),
-            GeometryBox::ViewBox => dest.write_str("view-box"),
-            GeometryBox::ShapeBox(s) => s.to_css(dest),
-        }
-    }
-}
-
 impl<L> ToCss for InsetRect<L>
     where L: ToCss + PartialEq
 {
diff --git a/components/style/values/generics/border.rs b/components/style/values/generics/border.rs
index f1384e580e3..5d8c9032e6a 100644
--- a/components/style/values/generics/border.rs
+++ b/components/style/values/generics/border.rs
@@ -11,7 +11,7 @@ use values::generics::rect::Rect;
 
 /// A generic value for a single side of a `border-image-width` property.
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToComputedValue)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToComputedValue, ToCss)]
 pub enum BorderImageSideWidth<LengthOrPercentage, Number> {
     /// `<length-or-percentage>`
     Length(LengthOrPercentage),
@@ -52,20 +52,6 @@ pub struct BorderRadius<LengthOrPercentage> {
 /// A generic value for `border-*-radius` longhand properties.
 pub struct BorderCornerRadius<L>(pub Size2D<L>);
 
-impl<L, N> ToCss for BorderImageSideWidth<L, N>
-    where L: ToCss, N: ToCss,
-{
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
-        where W: fmt::Write
-    {
-        match *self {
-            BorderImageSideWidth::Length(ref length) => length.to_css(dest),
-            BorderImageSideWidth::Number(ref number) => number.to_css(dest),
-            BorderImageSideWidth::Auto => dest.write_str("auto"),
-        }
-    }
-}
-
 impl<N> From<N> for BorderImageSlice<N>
     where N: Clone,
 {
diff --git a/components/style/values/generics/grid.rs b/components/style/values/generics/grid.rs
index 73640a91e49..3775bb30597 100644
--- a/components/style/values/generics/grid.rs
+++ b/components/style/values/generics/grid.rs
@@ -329,8 +329,8 @@ pub fn concat_serialize_idents<W>(prefix: &str, suffix: &str,
 /// The initial argument of the `repeat` function.
 ///
 /// https://drafts.csswg.org/css-grid/#typedef-track-repeat
-#[derive(Clone, Copy, PartialEq, Debug)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Clone, Copy, Debug, PartialEq, ToCss)]
 pub enum RepeatCount {
     /// A positive integer. This is allowed only for `<track-repeat>` and `<fixed-repeat>`
     Number(Integer),
@@ -340,16 +340,6 @@ pub enum RepeatCount {
     AutoFit,
 }
 
-impl ToCss for RepeatCount {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-        match *self {
-            RepeatCount::Number(ref c) => c.to_css(dest),
-            RepeatCount::AutoFill => dest.write_str("auto-fill"),
-            RepeatCount::AutoFit => dest.write_str("auto-fit"),
-        }
-    }
-}
-
 impl Parse for RepeatCount {
     fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
         if let Ok(i) = input.try(|i| Integer::parse(context, i)) {
diff --git a/components/style/values/generics/mod.rs b/components/style/values/generics/mod.rs
index ef88d7c342c..40d3f4e46df 100644
--- a/components/style/values/generics/mod.rs
+++ b/components/style/values/generics/mod.rs
@@ -182,8 +182,8 @@ impl<T: Parse> Parse for FontSettingTag<T> {
 
 
 /// A font settings value for font-variation-settings or font-feature-settings
-#[derive(Clone, Debug, Eq, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Clone, Debug, Eq, PartialEq, ToCss)]
 pub enum FontSettings<T> {
     /// No settings (default)
     Normal,
@@ -191,15 +191,6 @@ pub enum FontSettings<T> {
     Tag(Vec<FontSettingTag<T>>)
 }
 
-impl<T: ToCss> ToCss for FontSettings<T> {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-        match *self {
-            FontSettings::Normal => dest.write_str("normal"),
-            FontSettings::Tag(ref ftvs) => ftvs.to_css(dest)
-        }
-    }
-}
-
 impl<T: Parse> Parse for FontSettings<T> {
     /// https://www.w3.org/TR/css-fonts-3/#propdef-font-feature-settings
     fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
@@ -290,8 +281,8 @@ pub struct SVGPaint<ColorType> {
 /// Whereas the spec only allows PaintServer
 /// to have a fallback, Gecko lets the context
 /// properties have a fallback as well.
-#[derive(Debug, Clone, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Clone, Debug, PartialEq, ToCss)]
 pub enum SVGPaintKind<ColorType> {
     /// `none`
     None,
@@ -378,18 +369,6 @@ impl<ColorType: Parse> Parse for SVGPaint<ColorType> {
     }
 }
 
-impl<ColorType: ToCss> ToCss for SVGPaintKind<ColorType> {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-        match *self {
-            SVGPaintKind::None => dest.write_str("none"),
-            SVGPaintKind::ContextStroke => dest.write_str("context-stroke"),
-            SVGPaintKind::ContextFill => dest.write_str("context-fill"),
-            SVGPaintKind::Color(ref color) => color.to_css(dest),
-            SVGPaintKind::PaintServer(ref server) => server.to_css(dest),
-        }
-    }
-}
-
 impl<ColorType: ToCss> ToCss for SVGPaint<ColorType> {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
         self.kind.to_css(dest)?;
diff --git a/components/style/values/generics/text.rs b/components/style/values/generics/text.rs
index 2ba5ae4af98..5a5a10bb9d9 100644
--- a/components/style/values/generics/text.rs
+++ b/components/style/values/generics/text.rs
@@ -11,9 +11,50 @@ use properties::animated_properties::Animatable;
 use std::fmt;
 use style_traits::ToCss;
 
-/// A generic spacing value for the `letter-spacing` and `word-spacing` properties.alloc
+/// A generic value for the `initial-letter` property.
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToComputedValue)]
+pub enum InitialLetter<Number, Integer> {
+    /// `normal`
+    Normal,
+    /// `<number> <integer>?`
+    Specified(Number, Option<Integer>),
+}
+
+impl<N, I> InitialLetter<N, I> {
+    /// Returns `normal`.
+    #[inline]
+    pub fn normal() -> Self {
+        InitialLetter::Normal
+    }
+}
+
+impl<N, I> ToCss for InitialLetter<N, I>
+where
+    N: ToCss,
+    I: ToCss,
+{
+    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
+    where
+        W: fmt::Write,
+    {
+        match *self {
+            InitialLetter::Normal => dest.write_str("normal"),
+            InitialLetter::Specified(ref size, ref sink) => {
+                size.to_css(dest)?;
+                if let Some(ref sink) = *sink {
+                    dest.write_str(" ")?;
+                    sink.to_css(dest)?;
+                }
+                Ok(())
+            },
+        }
+    }
+}
+
+/// A generic spacing value for the `letter-spacing` and `word-spacing` properties.
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToComputedValue, ToCss)]
 pub enum Spacing<Value> {
     /// `normal`
     Normal,
@@ -76,22 +117,9 @@ impl<Value> Animatable for Spacing<Value>
     }
 }
 
-impl<Value> ToCss for Spacing<Value>
-    where Value: ToCss,
-{
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
-        where W: fmt::Write
-    {
-        match *self {
-            Spacing::Normal => dest.write_str("normal"),
-            Spacing::Value(ref value) => value.to_css(dest),
-        }
-    }
-}
-
 /// A generic value for the `line-height` property.
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToCss)]
 pub enum LineHeight<Number, LengthOrPercentage> {
     /// `normal`
     Normal,
@@ -111,19 +139,3 @@ impl<N, L> LineHeight<N, L> {
         LineHeight::Normal
     }
 }
-
-impl<N, L> ToCss for LineHeight<N, L>
-    where N: ToCss, L: ToCss,
-{
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
-        where W: fmt::Write,
-    {
-        match *self {
-            LineHeight::Normal => dest.write_str("normal"),
-            #[cfg(feature = "gecko")]
-            LineHeight::MozBlockHeight => dest.write_str("-moz-block-height"),
-            LineHeight::Number(ref number) => number.to_css(dest),
-            LineHeight::Length(ref value) => value.to_css(dest),
-        }
-    }
-}
diff --git a/components/style/values/specified/border.rs b/components/style/values/specified/border.rs
index b931ef36245..53260bc8e33 100644
--- a/components/style/values/specified/border.rs
+++ b/components/style/values/specified/border.rs
@@ -7,8 +7,6 @@
 use app_units::Au;
 use cssparser::Parser;
 use parser::{Parse, ParserContext};
-use std::fmt;
-use style_traits::ToCss;
 use values::computed::{Context, ToComputedValue};
 use values::generics::border::BorderCornerRadius as GenericBorderCornerRadius;
 use values::generics::border::BorderImageSideWidth as GenericBorderImageSideWidth;
@@ -20,7 +18,7 @@ use values::specified::length::{Length, LengthOrPercentage};
 
 /// A specified value for a single side of the `border-width` property.
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq, ToCss)]
 pub enum BorderSideWidth {
     /// `thin`
     Thin,
@@ -73,17 +71,6 @@ impl Parse for BorderSideWidth {
     }
 }
 
-impl ToCss for BorderSideWidth {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-        match *self {
-            BorderSideWidth::Thin => dest.write_str("thin"),
-            BorderSideWidth::Medium => dest.write_str("medium"),
-            BorderSideWidth::Thick => dest.write_str("thick"),
-            BorderSideWidth::Length(ref length) => length.to_css(dest)
-        }
-    }
-}
-
 impl ToComputedValue for BorderSideWidth {
     type ComputedValue = Au;
 
diff --git a/components/style/values/specified/length.rs b/components/style/values/specified/length.rs
index 61335ee0e55..e7b49ee9392 100644
--- a/components/style/values/specified/length.rs
+++ b/components/style/values/specified/length.rs
@@ -894,9 +894,9 @@ impl LengthOrPercentage {
 }
 
 /// Either a `<length>`, a `<percentage>`, or the `auto` keyword.
-#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq, ToCss)]
 pub enum LengthOrPercentageOrAuto {
     Length(NoCalcLength),
     Percentage(Percentage),
@@ -918,17 +918,6 @@ impl From<Percentage> for LengthOrPercentageOrAuto {
     }
 }
 
-impl ToCss for LengthOrPercentageOrAuto {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-        match *self {
-            LengthOrPercentageOrAuto::Length(ref length) => length.to_css(dest),
-            LengthOrPercentageOrAuto::Percentage(percentage) => percentage.to_css(dest),
-            LengthOrPercentageOrAuto::Auto => dest.write_str("auto"),
-            LengthOrPercentageOrAuto::Calc(ref calc) => calc.to_css(dest),
-        }
-    }
-}
-
 impl LengthOrPercentageOrAuto {
     fn parse_internal(context: &ParserContext,
                       input: &mut Parser,
@@ -1012,8 +1001,8 @@ impl LengthOrPercentageOrAuto {
 }
 
 /// Either a `<length>`, a `<percentage>`, or the `none` keyword.
-#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq, ToCss)]
 #[allow(missing_docs)]
 pub enum LengthOrPercentageOrNone {
     Length(NoCalcLength),
@@ -1022,16 +1011,6 @@ pub enum LengthOrPercentageOrNone {
     None,
 }
 
-impl ToCss for LengthOrPercentageOrNone {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-        match *self {
-            LengthOrPercentageOrNone::Length(ref length) => length.to_css(dest),
-            LengthOrPercentageOrNone::Percentage(ref percentage) => percentage.to_css(dest),
-            LengthOrPercentageOrNone::Calc(ref calc) => calc.to_css(dest),
-            LengthOrPercentageOrNone::None => dest.write_str("none"),
-        }
-    }
-}
 impl LengthOrPercentageOrNone {
     fn parse_internal(context: &ParserContext,
                       input: &mut Parser,
@@ -1099,8 +1078,8 @@ pub type LengthOrAuto = Either<Length, Auto>;
 
 /// Either a `<length>` or a `<percentage>` or the `auto` keyword or the
 /// `content` keyword.
-#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq, ToCss)]
 pub enum LengthOrPercentageOrAutoOrContent {
     /// A `<length>`.
     Length(NoCalcLength),
@@ -1156,18 +1135,6 @@ impl LengthOrPercentageOrAutoOrContent {
     }
 }
 
-impl ToCss for LengthOrPercentageOrAutoOrContent {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-        match *self {
-            LengthOrPercentageOrAutoOrContent::Length(ref len) => len.to_css(dest),
-            LengthOrPercentageOrAutoOrContent::Percentage(perc) => perc.to_css(dest),
-            LengthOrPercentageOrAutoOrContent::Auto => dest.write_str("auto"),
-            LengthOrPercentageOrAutoOrContent::Content => dest.write_str("content"),
-            LengthOrPercentageOrAutoOrContent::Calc(ref calc) => calc.to_css(dest),
-        }
-    }
-}
-
 /// Either a `<length>` or a `<number>`.
 pub type LengthOrNumber = Either<Length, Number>;
 
diff --git a/components/style/values/specified/mod.rs b/components/style/values/specified/mod.rs
index d7046451336..59ff135c303 100644
--- a/components/style/values/specified/mod.rs
+++ b/components/style/values/specified/mod.rs
@@ -45,7 +45,7 @@ pub use self::length::{Percentage, LengthOrNone, LengthOrNumber, LengthOrPercent
 pub use self::length::{LengthOrPercentageOrNone, LengthOrPercentageOrAutoOrContent, NoCalcLength};
 pub use self::length::{MaxLength, MozLength};
 pub use self::position::{Position, PositionComponent};
-pub use self::text::{LetterSpacing, LineHeight, WordSpacing};
+pub use self::text::{InitialLetter, LetterSpacing, LineHeight, WordSpacing};
 pub use self::transform::{TimingFunction, TransformOrigin};
 pub use super::generics::grid::GridLine;
 
diff --git a/components/style/values/specified/text.rs b/components/style/values/specified/text.rs
index cc517ad4abb..2d277e143ee 100644
--- a/components/style/values/specified/text.rs
+++ b/components/style/values/specified/text.rs
@@ -9,10 +9,15 @@ use parser::{Parse, ParserContext};
 use std::ascii::AsciiExt;
 use values::computed::{Context, ToComputedValue};
 use values::computed::text::LineHeight as ComputedLineHeight;
-use values::generics::text::{LineHeight as GenericLineHeight, Spacing};
-use values::specified::{AllowQuirks, Number};
+use values::generics::text::InitialLetter as GenericInitialLetter;
+use values::generics::text::LineHeight as GenericLineHeight;
+use values::generics::text::Spacing;
+use values::specified::{AllowQuirks, Integer, Number};
 use values::specified::length::{FontRelativeLength, Length, LengthOrPercentage, NoCalcLength};
 
+/// A specified type for the `initial-letter` property.
+pub type InitialLetter = GenericInitialLetter<Number, Integer>;
+
 /// A specified value for the `letter-spacing` property.
 pub type LetterSpacing = Spacing<Length>;
 
@@ -22,6 +27,17 @@ pub type WordSpacing = Spacing<LengthOrPercentage>;
 /// A specified value for the `line-height` property.
 pub type LineHeight = GenericLineHeight<Number, LengthOrPercentage>;
 
+impl Parse for InitialLetter {
+    fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
+        if input.try(|i| i.expect_ident_matching("normal")).is_ok() {
+            return Ok(GenericInitialLetter::Normal);
+        }
+        let size = Number::parse_at_least_one(context, input)?;
+        let sink = input.try(|i| Integer::parse_positive(context, i)).ok();
+        Ok(GenericInitialLetter::Specified(size, sink))
+    }
+}
+
 impl Parse for LetterSpacing {
     fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
         Spacing::parse_with(context, input, |c, i| {
diff --git a/components/style/values/specified/transform.rs b/components/style/values/specified/transform.rs
index f41539fc5b2..e0e5b1c2d6f 100644
--- a/components/style/values/specified/transform.rs
+++ b/components/style/values/specified/transform.rs
@@ -7,8 +7,6 @@
 use cssparser::Parser;
 use euclid::Point2D;
 use parser::{Parse, ParserContext};
-use std::fmt;
-use style_traits::ToCss;
 use values::computed::{LengthOrPercentage as ComputedLengthOrPercentage, Context, ToComputedValue};
 use values::computed::transform::TimingFunction as ComputedTimingFunction;
 use values::generics::transform::{StepPosition, TimingFunction as GenericTimingFunction};
@@ -22,7 +20,7 @@ pub type TransformOrigin = GenericTransformOrigin<OriginComponent<X>, OriginComp
 
 /// The specified value of a component of a CSS `<transform-origin>`.
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq, ToCss)]
 pub enum OriginComponent<S> {
     /// `center`
     Center,
@@ -99,20 +97,6 @@ impl<S> Parse for OriginComponent<S>
     }
 }
 
-impl<S: ToCss> ToCss for OriginComponent<S>
-    where S: ToCss,
-{
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
-        where W: fmt::Write,
-    {
-        match *self {
-            OriginComponent::Center => dest.write_str("center"),
-            OriginComponent::Length(ref lop) => lop.to_css(dest),
-            OriginComponent::Side(ref keyword) => keyword.to_css(dest),
-        }
-    }
-}
-
 impl<S> ToComputedValue for OriginComponent<S>
     where S: Side,
 {