Change ToCss to take a CssWriter<W>

This more concrete wrapper type can write a prefix the very first time something
is written to it. This allows removing plenty of useless monomorphisations caused
by the former W/SequenceWriter<W> pair of types.

components/style/values/specified/align.rs

@@ -11,8 +11,8 @@ use gecko_bindings::structs;
 use parser::{Parse, ParserContext};
 use selectors::parser::SelectorParseErrorKind;
 #[allow(unused_imports)] use std::ascii::AsciiExt;
-use std::fmt;
-use style_traits::{ToCss, ParseError, StyleParseErrorKind};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 
 bitflags! {
     /// Constants shared by multiple CSS Box Alignment properties
@@ -71,7 +71,10 @@ bitflags! {
 }
 
 impl ToCss for AlignFlags {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         let s = match *self & !AlignFlags::FLAG_BITS {
             AlignFlags::AUTO => "auto",
             AlignFlags::NORMAL => "normal",
@@ -209,7 +212,10 @@ impl AlignJustifyContent {
 }
 
 impl ToCss for AlignJustifyContent {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         self.primary().to_css(dest)?;
         match self.fallback() {
             AlignFlags::AUTO => {}

components/style/values/specified/angle.rs

@@ -7,8 +7,8 @@
 use cssparser::{Parser, Token};
 use parser::{ParserContext, Parse};
 #[allow(unused_imports)] use std::ascii::AsciiExt;
-use std::fmt;
-use style_traits::{ToCss, ParseError};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, ToCss};
 use values::CSSFloat;
 use values::computed::{Context, ToComputedValue};
 use values::computed::angle::Angle as ComputedAngle;
@@ -27,7 +27,10 @@ pub struct Angle {
 }
 
 impl ToCss for Angle {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         if self.was_calc {
             dest.write_str("calc(")?;
         }

components/style/values/specified/basic_shape.rs

@@ -10,8 +10,8 @@
 use cssparser::Parser;
 use parser::{Parse, ParserContext};
 use std::borrow::Cow;
-use std::fmt;
-use style_traits::{ToCss, ParseError, StyleParseErrorKind};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use values::computed::Percentage;
 use values::generics::basic_shape::{Circle as GenericCircle};
 use values::generics::basic_shape::{ClippingShape as GenericClippingShape, Ellipse as GenericEllipse};
@@ -171,7 +171,10 @@ impl Circle {
 }
 
 impl ToCss for Circle {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         dest.write_str("circle(")?;
         if GenericShapeRadius::ClosestSide != self.radius {
             self.radius.to_css(dest)?;
@@ -213,7 +216,10 @@ impl Ellipse {
 }
 
 impl ToCss for Ellipse {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         dest.write_str("ellipse(")?;
         if self.semiaxis_x != ShapeRadius::default() || self.semiaxis_y != ShapeRadius::default() {
             self.semiaxis_x.to_css(dest)?;
@@ -248,8 +254,12 @@ impl Parse for ShapeRadius {
 /// are converted to percentages where possible. Only the two or four
 /// value forms are used. In case of two keyword-percentage pairs,
 /// the keywords are folded into the percentages
-fn serialize_basicshape_position<W>(position: &Position, dest: &mut W) -> fmt::Result
-    where W: fmt::Write
+fn serialize_basicshape_position<W>(
+    position: &Position,
+    dest: &mut CssWriter<W>,
+) -> fmt::Result
+where
+    W: Write,
 {
     fn to_keyword_and_lop<S>(component: &PositionComponent<S>) -> (S, Cow<LengthOrPercentage>)
         where S: Copy + Side
@@ -289,8 +299,11 @@ fn serialize_basicshape_position<W>(position: &Position, dest: &mut W) -> fmt::R
         }
     }
 
-    fn write_pair<A, B, W>(a: &A, b: &B, dest: &mut W) -> fmt::Result
-        where A: ToCss, B: ToCss, W: fmt::Write
+    fn write_pair<A, B, W>(a: &A, b: &B, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        A: ToCss,
+        B: ToCss,
+        W: Write,
     {
         a.to_css(dest)?;
         dest.write_str(" ")?;

components/style/values/specified/box.rs

@@ -8,8 +8,8 @@ use Atom;
 use cssparser::Parser;
 use parser::{Parse, ParserContext};
 use selectors::parser::SelectorParseErrorKind;
-use std::fmt;
-use style_traits::{ParseError, ToCss, StyleParseErrorKind};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use values::CustomIdent;
 use values::KeyframesName;
 use values::generics::box_::AnimationIterationCount as GenericAnimationIterationCount;
@@ -289,9 +289,9 @@ impl AnimationName {
 }
 
 impl ToCss for AnimationName {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
     where
-        W: fmt::Write,
+        W: Write,
     {
         match self.0 {
             Some(ref name) => name.to_css(dest),
@@ -407,7 +407,10 @@ impl TouchAction {
 }
 
 impl ToCss for TouchAction {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         match *self {
             TouchAction::TOUCH_ACTION_NONE => dest.write_str("none"),
             TouchAction::TOUCH_ACTION_AUTO => dest.write_str("auto"),
@@ -497,7 +500,10 @@ bitflags! {
 }
 
 impl ToCss for Contain {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         if self.is_empty() {
             return dest.write_str("none")
         }

components/style/values/specified/calc.rs

@@ -9,8 +9,8 @@
 use cssparser::{Parser, Token, NumberOrPercentage, AngleOrNumber};
 use parser::ParserContext;
 #[allow(unused_imports)] use std::ascii::AsciiExt;
-use std::fmt;
-use style_traits::{ToCss, ParseError, StyleParseErrorKind};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use style_traits::values::specified::AllowedNumericType;
 use values::{CSSInteger, CSSFloat};
 use values::computed;
@@ -89,7 +89,10 @@ impl ToCss for CalcLengthOrPercentage {
     ///
     /// FIXME(emilio): Should this simplify away zeros?
     #[allow(unused_assignments)]
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         use num_traits::Zero;
 
         let mut first_value = true;

components/style/values/specified/color.rs

@@ -12,9 +12,9 @@ use itoa;
 use parser::{ParserContext, Parse};
 #[cfg(feature = "gecko")]
 use properties::longhands::system_colors::SystemColor;
-use std::fmt;
-use std::io::Write;
-use style_traits::{ToCss, ParseError, StyleParseErrorKind, ValueParseErrorKind};
+use std::fmt::{self, Write};
+use std::io::Write as IoWrite;
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss, ValueParseErrorKind};
 use super::AllowQuirks;
 use values::computed::{Color as ComputedColor, Context, ToComputedValue};
 use values::specified::calc::CalcNode;
@@ -187,7 +187,10 @@ impl Parse for Color {
 }
 
 impl ToCss for Color {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         match *self {
             Color::CurrentColor => CSSParserColor::CurrentColor.to_css(dest),
             Color::Numeric { authored: Some(ref authored), .. } => dest.write_str(authored),

components/style/values/specified/font.rs

@@ -16,8 +16,8 @@ use parser::{Parse, ParserContext};
 use properties::longhands::system_font::SystemFont;
 #[allow(unused_imports)]
 use std::ascii::AsciiExt;
-use std::fmt;
-use style_traits::{ToCss, StyleParseErrorKind, ParseError};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use values::CustomIdent;
 use values::computed::{font as computed, Context, Length, NonNegativeLength, ToComputedValue};
 use values::computed::font::{SingleFontFamily, FontFamilyList, FamilyName};
@@ -144,7 +144,10 @@ pub enum FontSize {
 }
 
 impl ToCss for FontSize {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         match *self {
             FontSize::Length(ref lop) => lop.to_css(dest),
             FontSize::Keyword(info) => info.kw.to_css(dest),
@@ -243,7 +246,10 @@ impl MallocSizeOf for FontFamily {
 }
 
 impl ToCss for FontFamily {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         match *self {
             FontFamily::Values(ref v) => {
                 let mut iter = v.iter();
@@ -408,7 +414,10 @@ impl Default for KeywordSize {
 }
 
 impl ToCss for KeywordSize {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         dest.write_str(match *self {
             KeywordSize::XXSmall => "xx-small",
             KeywordSize::XSmall => "x-small",
@@ -824,7 +833,10 @@ impl VariantAlternatesList {
 }
 
 impl ToCss for VariantAlternatesList {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         if self.0.is_empty() {
             return dest.write_str("normal");
         }
@@ -1031,7 +1043,10 @@ impl VariantEastAsian {
 }
 
 impl ToCss for VariantEastAsian {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         if self.is_empty() {
             return dest.write_str("normal")
         }
@@ -1265,7 +1280,10 @@ impl VariantLigatures {
 }
 
 impl ToCss for VariantLigatures {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         if self.is_empty() {
             return dest.write_str("normal")
         }
@@ -1506,7 +1524,10 @@ impl VariantNumeric {
 }
 
 impl ToCss for VariantNumeric {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         if self.is_empty() {
             return dest.write_str("normal")
         }
@@ -1801,7 +1822,10 @@ impl Parse for FontSynthesis {
 }
 
 impl ToCss for FontSynthesis {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         if self.weight && self.style {
             dest.write_str("weight style")
         } else if self.style {
@@ -1953,7 +1977,10 @@ impl Parse for XTextZoom {
 }
 
 impl ToCss for XTextZoom {
-    fn to_css<W>(&self, _: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, _: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         Ok(())
     }
 }
@@ -1981,7 +2008,10 @@ impl Parse for XLang {
 }
 
 impl ToCss for XLang {
-    fn to_css<W>(&self, _: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, _: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         Ok(())
     }
 }

components/style/values/specified/image.rs

@@ -16,8 +16,8 @@ use selectors::parser::SelectorParseErrorKind;
 use servo_url::ServoUrl;
 use std::cmp::Ordering;
 use std::f32::consts::PI;
-use std::fmt;
-use style_traits::{ToCss, ParseError, StyleParseErrorKind};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use values::{Either, None_};
 #[cfg(feature = "gecko")]
 use values::computed::{Context, Position as ComputedPosition, ToComputedValue};
@@ -659,8 +659,13 @@ impl GenericsLineDirection for LineDirection {
         }
     }
 
-    fn to_css<W>(&self, dest: &mut W, compat_mode: CompatMode) -> fmt::Result
-        where W: fmt::Write
+    fn to_css<W>(
+        &self,
+        dest: &mut CssWriter<W>,
+        compat_mode: CompatMode,
+    ) -> fmt::Result
+    where
+        W: Write,
     {
         match *self {
             LineDirection::Angle(angle) => {

components/style/values/specified/inherited_box.rs

@@ -7,8 +7,8 @@
 use cssparser::Parser;
 use parser::{Parse, ParserContext};
 use std::f64::consts::PI;
-use std::fmt;
-use style_traits::{ParseError, StyleParseErrorKind, ToCss};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use values::computed;
 use values::computed::{Context, Orientation, ToComputedValue};
 use values::specified::Angle;
@@ -25,7 +25,10 @@ pub struct ImageOrientation {
 }
 
 impl ToCss for ImageOrientation {
-    fn to_css<W: fmt::Write>(&self, dest: &mut W) -> fmt::Result {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         if let Some(angle) = self.angle {
             angle.to_css(dest)?;
             if self.flipped {

components/style/values/specified/list.rs

@@ -6,8 +6,8 @@
 
 use cssparser::{Parser, Token};
 use parser::{Parse, ParserContext};
-use std::fmt;
-use style_traits::{ParseError, StyleParseErrorKind, ToCss};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use values::{Either, None_};
 #[cfg(feature = "gecko")]
 use values::CustomIdent;
@@ -114,7 +114,10 @@ impl Parse for ListStyleImage {
 pub struct Quotes(pub Box<[(Box<str>, Box<str>)]>);
 
 impl ToCss for Quotes {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         let mut iter = self.0.iter();
 
         match iter.next() {

components/style/values/specified/mod.rs

@@ -13,8 +13,8 @@ use parser::{ParserContext, Parse};
 use self::url::SpecifiedUrl;
 #[allow(unused_imports)] use std::ascii::AsciiExt;
 use std::f32;
-use std::fmt;
-use style_traits::{ToCss, ParseError, StyleParseErrorKind};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use style_traits::values::specified::AllowedNumericType;
 use super::{Auto, CSSFloat, CSSInteger, Either, None_};
 use super::computed::{Context, ToComputedValue};
@@ -250,8 +250,9 @@ impl ToComputedValue for Number {
 }
 
 impl ToCss for Number {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
-        where W: fmt::Write,
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
     {
         if self.calc_clamping_mode.is_some() {
             dest.write_str("calc(")?;
@@ -476,8 +477,9 @@ impl ToComputedValue for Integer {
 }
 
 impl ToCss for Integer {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
-        where W: fmt::Write,
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
     {
         if self.was_calc {
             dest.write_str("calc(")?;
@@ -560,7 +562,10 @@ pub struct ClipRect {
 
 
 impl ToCss for ClipRect {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         dest.write_str("rect(")?;
 
         if let Some(ref top) = self.top {
@@ -805,7 +810,10 @@ impl Attr {
 }
 
 impl ToCss for Attr {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         dest.write_str("attr(")?;
         if let Some(ref ns) = self.namespace {
             serialize_identifier(&ns.0.to_string(), dest)?;

components/style/values/specified/percentage.rs

@@ -7,8 +7,8 @@
 use cssparser::{Parser, Token};
 use parser::{Parse, ParserContext};
 #[allow(unused_imports)] use std::ascii::AsciiExt;
-use std::fmt;
-use style_traits::{ParseError, ToCss};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, ToCss};
 use style_traits::values::specified::AllowedNumericType;
 use values::{CSSFloat, serialize_percentage};
 use values::computed::{Context, ToComputedValue};
@@ -29,8 +29,9 @@ pub struct Percentage {
 
 
 impl ToCss for Percentage {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
-        where W: fmt::Write,
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
     {
         if self.calc_clamping_mode.is_some() {
             dest.write_str("calc(")?;

components/style/values/specified/position.rs

@@ -11,10 +11,10 @@ use cssparser::Parser;
 use hash::FnvHashMap;
 use parser::{Parse, ParserContext};
 use selectors::parser::SelectorParseErrorKind;
-use std::fmt;
+use std::fmt::{self, Write};
 use std::ops::Range;
 use str::HTML_SPACE_CHARACTERS;
-use style_traits::{ToCss, StyleParseErrorKind, ParseError};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use values::{Either, None_};
 use values::computed::{CalcLengthOrPercentage, LengthOrPercentage as ComputedLengthOrPercentage};
 use values::computed::{Context, Percentage, ToComputedValue};
@@ -142,7 +142,10 @@ impl Position {
 }
 
 impl ToCss for Position {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         match (&self.horizontal, &self.vertical) {
             (x_pos @ &PositionComponent::Side(_, Some(_)), &PositionComponent::Length(ref y_lop)) => {
                 x_pos.to_css(dest)?;
@@ -369,7 +372,10 @@ impl LegacyPosition {
 }
 
 impl ToCss for LegacyPosition {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         self.horizontal.to_css(dest)?;
         dest.write_str(" ")?;
         self.vertical.to_css(dest)
@@ -409,7 +415,10 @@ impl GridAutoFlow {
 }
 
 impl ToCss for GridAutoFlow {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         self.autoflow.to_css(dest)?;
 
         if self.dense { dest.write_str(" dense")?; }
@@ -584,7 +593,10 @@ impl TemplateAreas {
 }
 
 impl ToCss for TemplateAreas {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         for (i, string) in self.strings.iter().enumerate() {
             if i != 0 {
                 dest.write_str(" ")?;

components/style/values/specified/svg.rs

@@ -6,8 +6,9 @@
 
 use cssparser::Parser;
 use parser::{Parse, ParserContext};
-use std::fmt;
-use style_traits::{CommaWithSpace, ParseError, Separator, StyleParseErrorKind, ToCss};
+use std::fmt::{self, Write};
+use style_traits::{CommaWithSpace, CssWriter, ParseError, Separator};
+use style_traits::{StyleParseErrorKind, ToCss};
 use values::CustomIdent;
 use values::generics::svg as generic;
 use values::specified::{LengthOrPercentage, NonNegativeLengthOrPercentage, NonNegativeNumber};
@@ -237,7 +238,10 @@ impl Parse for SVGPaintOrder {
 }
 
 impl ToCss for SVGPaintOrder {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         if self.0 == 0 {
             return dest.write_str("normal")
         }

components/style/values/specified/table.rs

@@ -7,7 +7,7 @@
 use cssparser::Parser;
 use parser::{Parse, ParserContext};
 use std::fmt;
-use style_traits::{ToCss, StyleParseErrorKind, ParseError};
+use style_traits::{CssWriter, ToCss, StyleParseErrorKind, ParseError};
 
 #[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToComputedValue)]
 /// span. for `<col span>` pres attr
@@ -21,7 +21,7 @@ impl Parse for XSpan {
 }
 
 impl ToCss for XSpan {
-    fn to_css<W>(&self, _: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, _: &mut CssWriter<W>) -> fmt::Result where W: fmt::Write {
         Ok(())
     }
 }

components/style/values/specified/text.rs

@@ -8,8 +8,8 @@ use cssparser::{Parser, Token};
 use parser::{Parse, ParserContext};
 use selectors::parser::SelectorParseErrorKind;
 #[allow(unused_imports)] use std::ascii::AsciiExt;
-use std::fmt;
-use style_traits::{ParseError, StyleParseErrorKind, ToCss};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use values::computed::{Context, ToComputedValue};
 use values::computed::text::LineHeight as ComputedLineHeight;
 use values::computed::text::TextOverflow as ComputedTextOverflow;
@@ -440,7 +440,10 @@ impl Parse for TextAlign {
 }
 
 impl ToCss for TextAlign {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         match *self {
             TextAlign::Keyword(key) => key.to_css(dest),
             #[cfg(feature = "gecko")]

components/style/values/specified/time.rs

@@ -7,8 +7,8 @@
 use cssparser::{Parser, Token};
 use parser::{ParserContext, Parse};
 #[allow(unused_imports)] use std::ascii::AsciiExt;
-use std::fmt;
-use style_traits::{ToCss, ParseError, StyleParseErrorKind};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use style_traits::values::specified::AllowedNumericType;
 use values::CSSFloat;
 use values::computed::{Context, ToComputedValue};
@@ -133,9 +133,9 @@ impl Parse for Time {
 }
 
 impl ToCss for Time {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
     where
-        W: fmt::Write,
+        W: Write,
     {
         if self.was_calc {
             dest.write_str("calc(")?;

components/style/values/specified/ui.rs

@@ -6,8 +6,8 @@
 
 use cssparser::Parser;
 use parser::{Parse, ParserContext};
-use std::fmt;
-use style_traits::{ParseError, StyleParseErrorKind, ToCss};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 
 /// Specified value of `-moz-force-broken-image-icon`
 #[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToComputedValue)]
@@ -36,7 +36,10 @@ impl Parse for MozForceBrokenImageIcon {
 }
 
 impl ToCss for MozForceBrokenImageIcon {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
         dest.write_str(if self.0 { "1" } else { "0" })
     }
 }