style: Use Rust types for some misc properties.

-moz-tab-size, border-image-outset and border-image-slice.

This is not a particularly interesting patch, just removes some code. We can
remove way more code when a few related properties are also ported.

Differential Revision: https://phabricator.services.mozilla.com/D19825

components/style/cbindgen.toml

@@ -87,19 +87,22 @@ include = [
   "FlexBasis",
   "Position",
   "BackgroundSize",
+  "BorderImageSlice",
+  "NonNegativeLengthOrNumberRect",
 ]
 item_types = ["enums", "structs", "typedefs"]
 
 [export.body]
+"CSSPixelLength" = """
+  inline nscoord ToAppUnits() const;
+"""
+
 "LengthPercentage" = """
   // Defined in nsStyleCoord.h
   static constexpr inline StyleLengthPercentage Zero();
   static inline StyleLengthPercentage FromAppUnits(nscoord);
   static inline StyleLengthPercentage FromPercentage(float);
   inline CSSCoord LengthInCSSPixels() const;
- private:
-  inline nscoord LengthComponent() const;
- public:
   inline float Percentage() const;
   inline bool HasPercent() const;
   inline bool ConvertsToLength() const;

components/style/properties/gecko.mako.rs

@@ -61,7 +61,6 @@ use crate::values::computed::font::FontSize;
 use crate::values::computed::effects::{BoxShadow, Filter, SimpleShadow};
 use crate::values::generics::column::ColumnCount;
 use crate::values::generics::position::ZIndex;
-use crate::values::generics::text::MozTabSize;
 use crate::values::generics::transform::TransformStyle;
 use crate::values::generics::url::UrlOrNone;
 
@@ -1371,6 +1370,9 @@ impl Clone for ${style_struct.gecko_struct_name} {
         "MozScriptMinSize": impl_absolute_length,
         "MozScriptSizeMultiplier": impl_simple,
         "NonNegativeLengthPercentage": impl_simple,
+        "NonNegativeLengthOrNumber": impl_simple,
+        "NonNegativeLengthOrNumberRect": impl_simple,
+        "BorderImageSlice": impl_simple,
         "NonNegativeNumber": impl_simple,
         "Number": impl_simple,
         "Opacity": impl_simple,
@@ -1476,8 +1478,8 @@ fn static_assert() {
                                      for x in CORNERS]) %>
 
 <%self:impl_trait style_struct_name="Border"
-                  skip_longhands="${skip_border_longhands} border-image-source border-image-outset
+                  skip_longhands="${skip_border_longhands} border-image-source
-                                  border-image-repeat border-image-width border-image-slice">
+                                  border-image-repeat border-image-width">
     % for side in SIDES:
     pub fn set_border_${side.ident}_style(&mut self, v: BorderStyle) {
         self.gecko.mBorderStyle[${side.index}] = v;
@@ -1578,8 +1580,6 @@ fn static_assert() {
         }
     }
 
-    <% impl_style_sides("border_image_outset") %>
-
     <%
     border_image_repeat_keywords = ["Stretch", "Repeat", "Round", "Space"]
     %>
@@ -1621,36 +1621,6 @@ fn static_assert() {
     }
 
     <% impl_style_sides("border_image_width") %>
-
-    pub fn set_border_image_slice(&mut self, v: longhands::border_image_slice::computed_value::T) {
-        use crate::gecko_bindings::structs::{NS_STYLE_BORDER_IMAGE_SLICE_NOFILL, NS_STYLE_BORDER_IMAGE_SLICE_FILL};
-
-        v.offsets.to_gecko_rect(&mut self.gecko.mBorderImageSlice);
-
-        let fill = if v.fill {
-            NS_STYLE_BORDER_IMAGE_SLICE_FILL
-        } else {
-            NS_STYLE_BORDER_IMAGE_SLICE_NOFILL
-        };
-        self.gecko.mBorderImageFill = fill as u8;
-    }
-
-    <%self:copy_sides_style_coord ident="border_image_slice">
-        self.gecko.mBorderImageFill = other.gecko.mBorderImageFill;
-    </%self:copy_sides_style_coord>
-
-    pub fn clone_border_image_slice(&self) -> longhands::border_image_slice::computed_value::T {
-        use crate::gecko_bindings::structs::NS_STYLE_BORDER_IMAGE_SLICE_FILL;
-        use crate::values::computed::{BorderImageSlice, NonNegativeNumberOrPercentage};
-        type NumberOrPercentageRect = crate::values::generics::rect::Rect<NonNegativeNumberOrPercentage>;
-
-        BorderImageSlice {
-            offsets:
-                NumberOrPercentageRect::from_gecko_rect(&self.gecko.mBorderImageSlice)
-                    .expect("mBorderImageSlice[${side}] could not convert to NumberOrPercentageRect"),
-            fill: self.gecko.mBorderImageFill as u32 == NS_STYLE_BORDER_IMAGE_SLICE_FILL
-        }
-    }
 </%self:impl_trait>
 
 <% skip_scroll_margin_longhands = " ".join(["scroll-margin-%s" % x.ident for x in SIDES]) %>
@@ -4377,7 +4347,7 @@ fn static_assert() {
 
 <%self:impl_trait style_struct_name="InheritedText"
                   skip_longhands="text-align text-emphasis-style text-shadow line-height letter-spacing word-spacing
-                                  -webkit-text-stroke-width text-emphasis-position -moz-tab-size">
+                                  -webkit-text-stroke-width text-emphasis-position">
 
     <% text_align_keyword = Keyword("text-align",
                                     "start end left right center justify -moz-center -moz-left -moz-right char",
@@ -4566,28 +4536,6 @@ fn static_assert() {
     ${impl_non_negative_length('_webkit_text_stroke_width',
                                'mWebkitTextStrokeWidth')}
 
-    #[allow(non_snake_case)]
-    pub fn set__moz_tab_size(&mut self, v: longhands::_moz_tab_size::computed_value::T) {
-        match v {
-            MozTabSize::Number(non_negative_number) => {
-                self.gecko.mTabSize.set_value(CoordDataValue::Factor(non_negative_number.0));
-            }
-            MozTabSize::Length(non_negative_length) => {
-                self.gecko.mTabSize.set(non_negative_length);
-            }
-        }
-    }
-
-    #[allow(non_snake_case)]
-    pub fn clone__moz_tab_size(&self) -> longhands::_moz_tab_size::computed_value::T {
-        match self.gecko.mTabSize.as_value() {
-            CoordDataValue::Coord(coord) => MozTabSize::Length(Au(coord).into()),
-            CoordDataValue::Factor(number) => MozTabSize::Number(From::from(number)),
-            _ => unreachable!(),
-        }
-    }
-
-    <%call expr="impl_coord_copy('_moz_tab_size', 'mTabSize')"></%call>
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="Text"

components/style/properties/longhands/border.mako.rs

@@ -119,10 +119,9 @@ ${helpers.predefined_type(
 
 ${helpers.predefined_type(
     "border-image-outset",
-    "LengthOrNumberRect",
+    "NonNegativeLengthOrNumberRect",
-    parse_method="parse_non_negative",
+    initial_value="generics::rect::Rect::all(computed::NonNegativeLengthOrNumber::zero())",
-    initial_value="computed::LengthOrNumberRect::all(computed::LengthOrNumber::zero())",
+    initial_specified_value="generics::rect::Rect::all(specified::NonNegativeLengthOrNumber::zero())",
-    initial_specified_value="specified::LengthOrNumberRect::all(specified::LengthOrNumber::zero())",
     spec="https://drafts.csswg.org/css-backgrounds/#border-image-outset",
     animation_value_type="discrete",
     flags="APPLIES_TO_FIRST_LETTER",

components/style/properties/longhands/inherited_text.mako.rs

@@ -257,10 +257,10 @@ ${helpers.predefined_type(
 
 ${helpers.predefined_type(
     "-moz-tab-size",
-    "MozTabSize",
+    "NonNegativeLengthOrNumber",
-    "generics::text::MozTabSize::Number(From::from(8.0))",
+    "generics::length::LengthOrNumber::Number(From::from(8.0))",
     products="gecko",
-    animation_value_type="AnimatedMozTabSize",
+    animation_value_type="LengthOrNumber",
     spec="https://drafts.csswg.org/css-text-3/#tab-size-property",
 )}
 
@@ -349,8 +349,8 @@ ${helpers.single_keyword(
     "-moz-control-character-visibility",
     "hidden visible",
     gecko_constant_prefix="NS_STYLE_CONTROL_CHARACTER_VISIBILITY",
-    gecko_ffi_name="mControlCharacterVisibility",
     animation_value_type="none",
+    gecko_ffi_name="mControlCharacterVisibility",
     products="gecko",
     spec="Nonstandard",
 )}

components/style/values/computed/length.rs

@@ -6,9 +6,10 @@
 
 use super::{Context, Number, Percentage, ToComputedValue};
 use crate::values::animated::ToAnimatedValue;
+use crate::values::computed::NonNegativeNumber;
 use crate::values::distance::{ComputeSquaredDistance, SquaredDistance};
 use crate::values::generics::length as generics;
-use crate::values::generics::length::{MaxSize as GenericMaxSize, Size as GenericSize};
+use crate::values::generics::length::{MaxSize as GenericMaxSize, Size as GenericSize, GenericLengthOrNumber};
 use crate::values::generics::transform::IsZeroLength;
 use crate::values::generics::NonNegative;
 use crate::values::specified::length::ViewportPercentageLength;
@@ -678,6 +679,15 @@ impl ToCss for CSSPixelLength {
     }
 }
 
+impl Add for CSSPixelLength {
+    type Output = Self;
+
+    #[inline]
+    fn add(self, other: Self) -> Self {
+        Self::new(self.px() + other.px())
+    }
+}
+
 impl Neg for CSSPixelLength {
     type Output = Self;
 
@@ -708,15 +718,7 @@ pub type Length = CSSPixelLength;
 pub type LengthOrAuto = Either<Length, Auto>;
 
 /// Either a computed `<length>` or a `<number>` value.
-pub type LengthOrNumber = Either<Length, Number>;
+pub type LengthOrNumber = GenericLengthOrNumber<Length, Number>;
-
-impl LengthOrNumber {
-    /// Returns `0`.
-    #[inline]
-    pub fn zero() -> Self {
-        Either::Second(0.)
-    }
-}
 
 /// Either a computed `<length>` or the `normal` keyword.
 pub type LengthOrNormal = Either<Length, Normal>;
@@ -776,13 +778,6 @@ impl NonNegativeLength {
     }
 }
 
-impl Add<NonNegativeLength> for NonNegativeLength {
-    type Output = Self;
-    fn add(self, other: Self) -> Self {
-        NonNegativeLength::new(self.px() + other.px())
-    }
-}
-
 impl From<Length> for NonNegativeLength {
     #[inline]
     fn from(len: Length) -> Self {
@@ -813,6 +808,9 @@ pub type NonNegativeLengthOrNormal = Either<NonNegativeLength, Normal>;
 /// Either a computed NonNegativeLengthPercentage or the `normal` keyword.
 pub type NonNegativeLengthPercentageOrNormal = Either<NonNegativeLengthPercentage, Normal>;
 
+/// Either a non-negative `<length>` or a `<number>`.
+pub type NonNegativeLengthOrNumber = GenericLengthOrNumber<NonNegativeLength, NonNegativeNumber>;
+
 /// A type for possible values for min- and max- flavors of width, height,
 /// block-size, and inline-size.
 #[allow(missing_docs)]

components/style/values/computed/mod.rs

@@ -61,7 +61,7 @@ pub use self::font::{MozScriptLevel, MozScriptMinSize, MozScriptSizeMultiplier,
 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};
+pub use self::length::{Length, LengthOrNumber, LengthPercentage, NonNegativeLengthOrNumber};
 pub use self::length::{LengthPercentageOrAuto, MaxSize, Size};
 pub use self::length::{NonNegativeLengthPercentage, NonNegativeLengthPercentageOrAuto};
 #[cfg(feature = "gecko")]
@@ -71,13 +71,13 @@ pub use self::motion::OffsetPath;
 pub use self::outline::OutlineStyle;
 pub use self::percentage::{NonNegativePercentage, Percentage};
 pub use self::position::{GridAutoFlow, GridTemplateAreas, Position, ZIndex};
-pub use self::rect::LengthOrNumberRect;
+pub use self::rect::NonNegativeLengthOrNumberRect;
 pub use self::resolution::Resolution;
 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, MozTabSize};
+pub use self::text::{InitialLetter, LetterSpacing, LineHeight};
 pub use self::text::{OverflowWrap, TextOverflow, WordSpacing};
 pub use self::text::{TextAlign, TextEmphasisPosition, TextEmphasisStyle};
 pub use self::time::Time;
@@ -536,6 +536,7 @@ impl From<GreaterThanOrEqualToOneNumber> for CSSFloat {
 
 #[allow(missing_docs)]
 #[derive(Clone, ComputeSquaredDistance, Copy, Debug, MallocSizeOf, PartialEq, ToCss)]
+#[repr(C, u8)]
 pub enum NumberOrPercentage {
     Percentage(Percentage),
     Number(Number),

components/style/values/computed/rect.rs

@@ -4,8 +4,8 @@
 
 //! Computed types for CSS borders.
 
-use crate::values::computed::length::LengthOrNumber;
+use crate::values::computed::length::NonNegativeLengthOrNumber;
 use crate::values::generics::rect::Rect;
 
 /// A specified rectangle made of four `<length-or-number>` values.
-pub type LengthOrNumberRect = Rect<LengthOrNumber>;
+pub type NonNegativeLengthOrNumberRect = Rect<NonNegativeLengthOrNumber>;

components/style/values/computed/text.rs

@@ -10,7 +10,6 @@ use crate::values::computed::length::{Length, LengthPercentage};
 use crate::values::computed::{NonNegativeLength, NonNegativeNumber};
 use crate::values::generics::text::InitialLetter as GenericInitialLetter;
 use crate::values::generics::text::LineHeight as GenericLineHeight;
-use crate::values::generics::text::MozTabSize as GenericMozTabSize;
 use crate::values::generics::text::Spacing;
 use crate::values::specified::text::TextOverflowSide;
 use crate::values::specified::text::{TextEmphasisFillMode, TextEmphasisShapeKeyword};
@@ -124,9 +123,6 @@ impl TextDecorationsInEffect {
     }
 }
 
-/// A specified value for the `-moz-tab-size` property.
-pub type MozTabSize = GenericMozTabSize<NonNegativeNumber, NonNegativeLength>;
-
 /// computed value for the text-emphasis-style property
 #[derive(Clone, Debug, MallocSizeOf, PartialEq, ToCss)]
 pub enum TextEmphasisStyle {

components/style/values/generics/border.rs

@@ -26,7 +26,8 @@ pub enum BorderImageSideWidth<LengthPercentage, Number> {
 #[derive(
     Clone, Copy, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToComputedValue, ToCss,
 )]
-pub struct BorderImageSlice<NumberOrPercentage> {
+#[repr(C)]
+pub struct GenericBorderImageSlice<NumberOrPercentage> {
     /// The offsets.
     #[css(field_bound)]
     pub offsets: Rect<NumberOrPercentage>,
@@ -35,6 +36,8 @@ pub struct BorderImageSlice<NumberOrPercentage> {
     pub fill: bool,
 }
 
+pub use self::GenericBorderImageSlice as BorderImageSlice;
+
 /// A generic value for the `border-*-radius` longhand properties.
 #[derive(
     Animate,

components/style/values/generics/length.rs

@@ -8,6 +8,7 @@ use crate::parser::{Parse, ParserContext};
 #[cfg(feature = "gecko")]
 use crate::values::computed::ExtremumLength;
 use cssparser::Parser;
+use num_traits::Zero;
 use style_traits::ParseError;
 
 /// A `<length-percentage> | auto` value.
@@ -155,3 +156,53 @@ impl<LengthPercentage> MaxSize<LengthPercentage> {
         MaxSize::None
     }
 }
+
+/// A generic `<length>` | `<number>` value for the `-moz-tab-size` property.
+#[derive(
+    Animate,
+    Clone,
+    ComputeSquaredDistance,
+    Copy,
+    Debug,
+    MallocSizeOf,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToAnimatedValue,
+    ToAnimatedZero,
+    ToComputedValue,
+    ToCss,
+)]
+#[repr(C, u8)]
+pub enum GenericLengthOrNumber<L, N> {
+    /// A length.
+    Length(L),
+    /// A number.
+    Number(N),
+}
+
+pub use self::GenericLengthOrNumber as LengthOrNumber;
+
+impl<L: Parse, N: Parse> Parse for LengthOrNumber<L, N> {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        if let Ok(number) = input.try(|i| N::parse(context, i)) {
+            // Numbers need to be parsed first because `0` must be recognised
+            // as the number `0` and not the length `0px`.
+            return Ok(LengthOrNumber::Number(number));
+        }
+
+        Ok(LengthOrNumber::Length(L::parse(context, input)?))
+    }
+}
+
+impl<L, N> LengthOrNumber<L, N> {
+    /// Returns `0`.
+    pub fn zero() -> Self
+    where
+        N: Zero,
+    {
+        LengthOrNumber::Number(num_traits::Zero::zero())
+    }
+}

components/style/values/generics/mod.rs

@@ -9,6 +9,8 @@ use super::CustomIdent;
 use crate::counter_style::{parse_counter_style_name, Symbols};
 use crate::parser::{Parse, ParserContext};
 use cssparser::Parser;
+use num_traits::Zero;
+use std::ops::Add;
 use style_traits::{KeywordsCollectFn, ParseError};
 use style_traits::{SpecifiedValueInfo, StyleParseErrorKind};
 
@@ -177,6 +179,24 @@ impl SpecifiedValueInfo for CounterStyleOrNone {
 #[repr(transparent)]
 pub struct NonNegative<T>(pub T);
 
+impl <T: Add<Output = T>> Add<NonNegative<T>> for NonNegative<T> {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        NonNegative(self.0 + other.0)
+    }
+}
+
+impl <T: Zero> Zero for NonNegative<T> {
+    fn is_zero(&self) -> bool {
+        self.0.is_zero()
+    }
+
+    fn zero() -> Self {
+        NonNegative(T::zero())
+    }
+}
+
 /// A wrapper of greater-than-or-equal-to-one values.
 #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
 #[derive(

components/style/values/generics/text.rs

@@ -149,25 +149,3 @@ impl<N, L> LineHeight<N, L> {
         LineHeight::Normal
     }
 }
-
-/// A generic value for the `-moz-tab-size` property.
-#[derive(
-    Animate,
-    Clone,
-    ComputeSquaredDistance,
-    Copy,
-    Debug,
-    MallocSizeOf,
-    PartialEq,
-    SpecifiedValueInfo,
-    ToAnimatedValue,
-    ToAnimatedZero,
-    ToComputedValue,
-    ToCss,
-)]
-pub enum MozTabSize<Number, Length> {
-    /// A number.
-    Number(Number),
-    /// A length.
-    Length(Length),
-}

components/style/values/specified/length.rs

@@ -11,9 +11,10 @@ use crate::font_metrics::FontMetricsQueryResult;
 use crate::parser::{Parse, ParserContext};
 use crate::values::computed::{self, CSSPixelLength, Context};
 use crate::values::generics::length as generics;
-use crate::values::generics::length::{MaxSize as GenericMaxSize, Size as GenericSize};
+use crate::values::generics::length::{MaxSize as GenericMaxSize, Size as GenericSize, GenericLengthOrNumber};
 use crate::values::generics::transform::IsZeroLength;
 use crate::values::generics::NonNegative;
+use crate::values::specified::NonNegativeNumber;
 use crate::values::specified::calc::CalcNode;
 use crate::values::{Auto, CSSFloat, Either, Normal};
 use app_units::Au;
@@ -1023,30 +1024,7 @@ pub type LengthOrNormal = Either<Length, Normal>;
 pub type LengthOrAuto = Either<Length, Auto>;
 
 /// Either a `<length>` or a `<number>`.
-pub type LengthOrNumber = Either<Length, Number>;
+pub type LengthOrNumber = GenericLengthOrNumber<Length, Number>;
-
-impl LengthOrNumber {
-    /// Parse a non-negative LengthOrNumber.
-    pub fn parse_non_negative<'i, 't>(
-        context: &ParserContext,
-        input: &mut Parser<'i, 't>,
-    ) -> Result<Self, ParseError<'i>> {
-        // We try to parse as a Number first because, for cases like
-        // LengthOrNumber, we want "0" to be parsed as a plain Number rather
-        // than a Length (0px); this matches the behaviour of all major browsers
-        if let Ok(v) = input.try(|i| Number::parse_non_negative(context, i)) {
-            return Ok(Either::Second(v));
-        }
-
-        Length::parse_non_negative(context, input).map(Either::First)
-    }
-
-    /// Returns `0`.
-    #[inline]
-    pub fn zero() -> Self {
-        Either::Second(Number::new(0.))
-    }
-}
 
 /// A specified value for `min-width`, `min-height`, `width` or `height` property.
 pub type Size = GenericSize<NonNegativeLengthPercentage>;
@@ -1123,3 +1101,6 @@ impl MaxSize {
         Ok(GenericMaxSize::LengthPercentage(length))
     }
 }
+
+/// A specified non-negative `<length>` | `<number>`.
+pub type NonNegativeLengthOrNumber = GenericLengthOrNumber<NonNegativeLength, NonNegativeNumber>;

components/style/values/specified/mod.rs

@@ -19,8 +19,9 @@ use crate::values::serialize_atom_identifier;
 use crate::values::specified::calc::CalcNode;
 use crate::{Atom, Namespace, Prefix};
 use cssparser::{Parser, Token};
-use num_traits::One;
+use num_traits::{Zero, One};
 use std::f32;
+use std::ops::Add;
 use std::fmt::{self, Write};
 use style_traits::values::specified::AllowedNumericType;
 use style_traits::{CssWriter, ParseError, SpecifiedValueInfo, StyleParseErrorKind, ToCss};
@@ -58,7 +59,7 @@ 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};
-pub use self::length::{FontRelativeLength, Length, LengthOrNumber};
+pub use self::length::{FontRelativeLength, Length, LengthOrNumber, NonNegativeLengthOrNumber};
 pub use self::length::{LengthPercentage, LengthPercentageOrAuto};
 pub use self::length::{MaxSize, Size};
 pub use self::length::{NoCalcLength, ViewportPercentageLength};
@@ -71,14 +72,14 @@ pub use self::outline::OutlineStyle;
 pub use self::percentage::Percentage;
 pub use self::position::{GridAutoFlow, GridTemplateAreas, Position};
 pub use self::position::{PositionComponent, ZIndex};
-pub use self::rect::LengthOrNumberRect;
+pub use self::rect::NonNegativeLengthOrNumberRect;
 pub use self::resolution::Resolution;
 pub use self::svg::MozContextProperties;
 pub use self::svg::{SVGLength, SVGOpacity, SVGPaint, SVGPaintKind};
 pub use self::svg::{SVGPaintOrder, SVGStrokeDashArray, SVGWidth};
 pub use self::svg_path::SVGPathData;
 pub use self::table::XSpan;
-pub use self::text::{InitialLetter, LetterSpacing, LineHeight, MozTabSize, TextAlign};
+pub use self::text::{InitialLetter, LetterSpacing, LineHeight, TextAlign};
 pub use self::text::{OverflowWrap, TextEmphasisPosition, TextEmphasisStyle};
 pub use self::text::{TextAlignKeyword, TextDecorationLine, TextOverflow, WordSpacing};
 pub use self::time::Time;
@@ -271,6 +272,26 @@ impl IsParallelTo for (Number, Number, Number) {
 
 impl SpecifiedValueInfo for Number {}
 
+impl Add for Number {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        Self::new(self.get() + other.get())
+    }
+}
+
+impl Zero for Number {
+    #[inline]
+    fn zero() -> Self {
+        Self::new(0.)
+    }
+
+    #[inline]
+    fn is_zero(&self) -> bool {
+        self.get() == 0.
+    }
+}
+
 impl From<Number> for f32 {
     #[inline]
     fn from(n: Number) -> Self {

components/style/values/specified/rect.rs

@@ -4,22 +4,8 @@
 
 //! Specified types for CSS borders.
 
-use crate::parser::ParserContext;
 use crate::values::generics::rect::Rect;
-use crate::values::specified::length::LengthOrNumber;
+use crate::values::specified::length::NonNegativeLengthOrNumber;
-use cssparser::Parser;
-use style_traits::ParseError;
 
 /// A specified rectangle made of four `<length-or-number>` values.
-pub type LengthOrNumberRect = Rect<LengthOrNumber>;
+pub type NonNegativeLengthOrNumberRect = Rect<NonNegativeLengthOrNumber>;
-
-impl LengthOrNumberRect {
-    /// Parses a `LengthOrNumberRect`, rejecting negative values.
-    #[inline]
-    pub fn parse_non_negative<'i, 't>(
-        context: &ParserContext,
-        input: &mut Parser<'i, 't>,
-    ) -> Result<Self, ParseError<'i>> {
-        Rect::parse_with(context, input, LengthOrNumber::parse_non_negative)
-    }
-}

components/style/values/specified/text.rs

@@ -13,11 +13,10 @@ use crate::values::computed::text::TextOverflow as ComputedTextOverflow;
 use crate::values::computed::{Context, ToComputedValue};
 use crate::values::generics::text::InitialLetter as GenericInitialLetter;
 use crate::values::generics::text::LineHeight as GenericLineHeight;
-use crate::values::generics::text::MozTabSize as GenericMozTabSize;
 use crate::values::generics::text::Spacing;
 use crate::values::specified::length::{FontRelativeLength, Length};
 use crate::values::specified::length::{LengthPercentage, NoCalcLength};
-use crate::values::specified::length::{NonNegativeLength, NonNegativeLengthPercentage};
+use crate::values::specified::length::{NonNegativeLengthPercentage};
 use crate::values::specified::{AllowQuirks, Integer, NonNegativeNumber, Number};
 use cssparser::{Parser, Token};
 use selectors::parser::SelectorParseErrorKind;
@@ -835,25 +834,6 @@ impl From<TextEmphasisPosition> for u8 {
     }
 }
 
-/// A specified value for the `-moz-tab-size` property.
-pub type MozTabSize = GenericMozTabSize<NonNegativeNumber, NonNegativeLength>;
-
-impl Parse for MozTabSize {
-    fn parse<'i, 't>(
-        context: &ParserContext,
-        input: &mut Parser<'i, 't>,
-    ) -> Result<Self, ParseError<'i>> {
-        if let Ok(number) = input.try(|i| NonNegativeNumber::parse(context, i)) {
-            // Numbers need to be parsed first because `0` must be recognised
-            // as the number `0` and not the length `0px`.
-            return Ok(GenericMozTabSize::Number(number));
-        }
-        Ok(GenericMozTabSize::Length(NonNegativeLength::parse(
-            context, input,
-        )?))
-    }
-}
-
 /// Values for the `overflow-wrap` property.
 #[repr(u8)]
 #[derive(