$

node_modules/clean-css/lib/optimizer/remove-unused.js

@@ -0,0 +1,11 @@
+function removeUnused(properties) {
+  for (var i = properties.length - 1; i >= 0; i--) {
+    var property = properties[i];
+
+    if (property.unused) {
+      property.all.splice(property.position, 1);
+    }
+  }
+}
+
+module.exports = removeUnused;