diff -rup thunderbird-60.6.1.orig/servo/components/style_traits/values.rs thunderbird-60.6.1/servo/components/style_traits/values.rs
--- thunderbird-60.6.1.orig/servo/components/style_traits/values.rs	2019-03-25 02:38:43.000000000 +0100
+++ thunderbird-60.6.1/servo/components/style_traits/values.rs	2019-03-30 12:31:55.070634646 +0100
@@ -135,6 +135,7 @@ where
     }
 }
 
+/// Documentation needed here, but the macro appears to be unused anyway...
 #[macro_export]
 macro_rules! serialize_function {
     ($dest: expr, $name: ident($( $arg: expr, )+)) => {
@@ -404,6 +405,8 @@ impl_to_css_for_predefined_type!(::csspa
 impl_to_css_for_predefined_type!(::cssparser::Color);
 impl_to_css_for_predefined_type!(::cssparser::UnicodeRange);
 
+
+/// Define an enum type with unit variants that each correspond to a CSS keyword.
 #[macro_export]
 macro_rules! define_css_keyword_enum {
     (pub enum $name:ident { $($variant:ident = $css:expr,)+ }) => {