style: Fix Servo build.

components/style/media_queries/media_feature_expression.rs

@@ -242,10 +242,14 @@ fn consume_operation_or_colon(input: &mut Parser) -> Result<Option<Operator>, ()
     }))
 }
 
+#[allow(unused_variables)]
 fn disabled_by_pref(feature: &Atom) -> bool {
+    #[cfg(feature = "gecko")]
+    {
         if *feature == atom!("-moz-touch-enabled") {
             return !static_prefs::pref!("layout.css.moz-touch-enabled.enabled");
         }
+    }
     false
 }
 

components/style/properties/properties.mako.rs

@@ -1877,12 +1877,15 @@ impl PropertyId {
             return Ok(match *id {
                 StaticId::Longhand(id) => PropertyId::Longhand(id),
                 StaticId::Shorthand(id) => {
+                    #[cfg(feature = "gecko")]
+                    {
                         // We want to count `zoom` even if disabled.
                         if matches!(id, ShorthandId::Zoom) {
                             if let Some(counters) = use_counters {
                                 counters.non_custom_properties.record(id.into());
                             }
                         }
+                    }
 
                     PropertyId::Shorthand(id)
                 },

components/style/values/computed/length.rs

@@ -607,7 +607,6 @@ impl Size {
 }
 
 /// The computed `<length>` value.
-#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
 #[derive(
     Animate,
     Clone,