Auto merge of #19220 - CYBAI:font-variant-east-asian-out-of-mako, r=emilio

style: Move font-variant-east-asian outside of mako

This is a sub-PR of #19015
r? emilio

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #19216
- [x] These changes do not require tests

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components/style/macros.rs

@@ -4,6 +4,16 @@
 
 //! Various macro helpers.
 
+macro_rules! exclusive_value {
+    (($value:ident, $set:expr) => $ident:path) => {
+        if $value.intersects($set) {
+            return Err(())
+        } else {
+            $ident
+        }
+    }
+}
+
 macro_rules! trivial_to_computed_value {
     ($name:ty) => {
         impl $crate::values::computed::ToComputedValue for $name {