So siehts ganz gut aus !

node_modules/clean-css/lib/optimizer/level-2/properties/is-component-of.js

@@ -0,0 +1,22 @@
+var compactable = require('../compactable');
+
+function isComponentOf(property1, property2, shallow) {
+  return isDirectComponentOf(property1, property2) ||
+    !shallow && !!compactable[property1.name].shorthandComponents && isSubComponentOf(property1, property2);
+}
+
+function isDirectComponentOf(property1, property2) {
+  var descriptor = compactable[property1.name];
+
+  return 'components' in descriptor && descriptor.components.indexOf(property2.name) > -1;
+}
+
+function isSubComponentOf(property1, property2) {
+  return property1
+    .components
+    .some(function (component) {
+      return isDirectComponentOf(component, property2);
+    });
+}
+
+module.exports = isComponentOf;