Derive ToCss for MediaList

This uncovered the fancy snowflake `use fmt::Write` in the impl of ToCss
for NonTSPseudoClass.

components/style/gecko/selector_parser.rs

@@ -66,7 +66,7 @@ apply_non_ts_list!(pseudo_class_name);
 impl ToCss for NonTSPseudoClass {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
         use cssparser::CssStringWriter;
-        use fmt::Write;
+        use std::fmt::Write;
         macro_rules! pseudo_class_serialize {
             (bare: [$(($css:expr, $name:ident, $gecko_type:tt, $state:tt, $flags:tt),)*],
              string: [$(($s_css:expr, $s_name:ident, $s_gecko_type:tt, $s_state:tt, $s_flags:tt),)*]) => {

components/style/lib.rs

@@ -133,9 +133,6 @@ pub mod traversal_flags;
 #[allow(non_camel_case_types)]
 pub mod values;
 
-use std::fmt::{self, Write};
-use style_traits::{CssWriter, ToCss};
-
 #[cfg(feature = "gecko")] pub use gecko_string_cache as string_cache;
 #[cfg(feature = "gecko")] pub use gecko_string_cache::Atom;
 #[cfg(feature = "gecko")] pub use gecko_string_cache::Namespace;
@@ -181,30 +178,6 @@ macro_rules! reexport_computed_values {
 }
 longhand_properties_idents!(reexport_computed_values);
 
-/// Serializes as CSS a comma-separated list of any `T` that supports being
-/// serialized as CSS.
-pub fn serialize_comma_separated_list<W, T>(
-    dest: &mut CssWriter<W>,
-    list: &[T],
-) -> fmt::Result
-where
-    W: Write,
-    T: ToCss,
-{
-    if list.is_empty() {
-        return Ok(());
-    }
-
-    list[0].to_css(dest)?;
-
-    for item in list.iter().skip(1) {
-        dest.write_str(", ")?;
-        item.to_css(dest)?;
-    }
-
-    Ok(())
-}
-
 #[cfg(feature = "gecko")] use gecko_string_cache::WeakAtom;
 #[cfg(feature = "servo")] use servo_atoms::Atom as WeakAtom;
 

components/style/media_queries.rs

@@ -13,7 +13,6 @@ use cssparser::{Token, ParserInput};
 use error_reporting::{ContextualParseError, ParseErrorReporter};
 use parser::{ParserContext, ParserErrorContext};
 use selectors::parser::SelectorParseErrorKind;
-use serialize_comma_separated_list;
 use std::fmt::{self, Write};
 use str::string_as_ascii_lowercase;
 use style_traits::{CssWriter, ToCss, ParseError, StyleParseErrorKind};
@@ -25,22 +24,14 @@ pub use servo::media_queries::{Device, Expression};
 pub use gecko::media_queries::{Device, Expression};
 
 /// A type that encapsulates a media query list.
-#[derive(Clone, Debug)]
 #[cfg_attr(feature = "servo", derive(MallocSizeOf))]
+#[css(comma, iterable)]
+#[derive(Clone, Debug, ToCss)]
 pub struct MediaList {
     /// The list of media queries.
     pub media_queries: Vec<MediaQuery>,
 }
 
-impl ToCss for MediaList {
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: Write,
-    {
-        serialize_comma_separated_list(dest, &self.media_queries)
-    }
-}
-
 impl MediaList {
     /// Create an empty MediaList.
     pub fn empty() -> Self {