Replace write! with to_css and write_str in some ToCss impls

components/style/values/mod.rs

@@ -36,6 +36,22 @@ define_keyword_type!(None_, "none");
 define_keyword_type!(Auto, "auto");
 define_keyword_type!(Normal, "normal");
 
+/// Serialize a normalized value into percentage.
+pub fn serialize_percentage<W>(value: CSSFloat, dest: &mut W)
+    -> fmt::Result where W: fmt::Write
+{
+    (value * 100.).to_css(dest)?;
+    dest.write_str("%")
+}
+
+/// Serialize a value with given unit into dest.
+pub fn serialize_dimension<W>(value: CSSFloat, unit: &str, dest: &mut W)
+    -> fmt::Result where W: fmt::Write
+{
+    value.to_css(dest)?;
+    dest.write_str(unit)
+}
+
 /// Convenience void type to disable some properties and values through types.
 #[cfg_attr(feature = "servo", derive(Deserialize, HeapSizeOf, Serialize))]
 #[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToComputedValue, ToCss)]