style: Document style_traits and deny missing docs on it.

components/style_traits/values.rs

@@ -2,6 +2,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+//! Helper types and traits for the handling of CSS values.
+
 use app_units::Au;
 use std::fmt;
 
@@ -78,13 +80,14 @@ macro_rules! __define_css_keyword_enum__add_optional_traits {
 #[macro_export]
 macro_rules! __define_css_keyword_enum__actual {
     ($name: ident [ $( $derived_trait: ident),* ] [ $( $css: expr => $variant: ident ),+ ]) => {
-        #[allow(non_camel_case_types)]
+        #[allow(non_camel_case_types, missing_docs)]
         #[derive(Clone, Eq, PartialEq, Copy, Hash, RustcEncodable, Debug $(, $derived_trait )* )]
         pub enum $name {
             $( $variant ),+
         }
 
         impl $name {
+            /// Parse this property from a CSS input stream.
             pub fn parse(input: &mut ::cssparser::Parser) -> Result<$name, ()> {
                 match_ignore_ascii_case! { try!(input.expect_ident()),
                                            $( $css => Ok($name::$variant), )+
@@ -105,18 +108,23 @@ macro_rules! __define_css_keyword_enum__actual {
     }
 }
 
+/// Helper types for the handling of specified values.
 pub mod specified {
     use app_units::Au;
 
+    /// Whether to allow negative values or not.
     #[repr(u8)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     #[derive(Clone, Copy, Debug, PartialEq, Eq)]
     pub enum AllowedNumericType {
+        /// Allow all kind of numeric values.
         All,
+        /// Allow only non-negative values.
         NonNegative
     }
 
     impl AllowedNumericType {
+        /// Whether value is valid for this allowed numeric type.
         #[inline]
         pub fn is_ok(&self, value: f32) -> bool {
             match *self {
@@ -125,6 +133,7 @@ pub mod specified {
             }
         }
 
+        /// Clamp the value following the rules of this numeric type.
         #[inline]
         pub fn clamp(&self, val: Au) -> Au {
             use std::cmp;