Move table -x-span outisde of mako

components/style/properties/longhand/table.mako.rs

@@ -10,35 +10,10 @@ ${helpers.single_keyword("table-layout", "auto fixed",
                          gecko_ffi_name="mLayoutStrategy", animation_value_type="discrete",
                          spec="https://drafts.csswg.org/css-tables/#propdef-table-layout")}
 
-<%helpers:longhand name="-x-span" products="gecko"
-                   spec="Internal-only (for `<col span>` pres attr)"
-                   animation_value_type="none"
-                   internal="True">
-    pub type SpecifiedValue = computed_value::T;
-    pub mod computed_value {
-        use std::fmt;
-        use style_traits::ToCss;
-
-        #[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToComputedValue)]
-        pub struct T(pub i32);
-
-        impl ToCss for T {
-            fn to_css<W>(&self, _: &mut W) -> fmt::Result where W: fmt::Write {
-                Ok(())
-            }
-        }
-    }
-
-    #[inline]
-    pub fn get_initial_value() -> computed_value::T {
-        computed_value::T(1)
-    }
-
-    // never parse it, only set via presentation attribute
-    fn parse<'i, 't>(
-        _: &ParserContext,
-        input: &mut Parser<'i, 't>,
-    ) -> Result<SpecifiedValue, ParseError<'i>> {
-        Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError))
-    }
-</%helpers:longhand>
+${helpers.predefined_type("-x-span",
+                          "XSpan",
+                          "computed::XSpan(1)",
+                          products="gecko",
+                          spec="Internal-only (for `<col span>` pres attr)",
+                          animation_value_type="none",
+                          internal=True)}