Add production dependencies

node_modules/clean-css/lib/optimizer/level-2/tidy-rule-duplicates.js

@@ -0,0 +1,21 @@
+function ruleSorter(s1, s2) {
+  return s1[1] > s2[1] ? 1 : -1;
+}
+
+function tidyRuleDuplicates(rules) {
+  var list = [];
+  var repeated = [];
+
+  for (var i = 0, l = rules.length; i < l; i++) {
+    var rule = rules[i];
+
+    if (repeated.indexOf(rule[1]) == -1) {
+      repeated.push(rule[1]);
+      list.push(rule);
+    }
+  }
+
+  return list.sort(ruleSorter);
+}
+
+module.exports = tidyRuleDuplicates;