add some packages

node_modules/clean-css/lib/optimizer/level-2/properties/vendor-prefixes.js

@@ -0,0 +1,23 @@
+var VENDOR_PREFIX_PATTERN = /(?:^|\W)(\-\w+\-)/g;
+
+function unique(value) {
+  var prefixes = [];
+  var match;
+
+  while ((match = VENDOR_PREFIX_PATTERN.exec(value)) !== null) {
+    if (prefixes.indexOf(match[0]) == -1) {
+      prefixes.push(match[0]);
+    }
+  }
+
+  return prefixes;
+}
+
+function same(value1, value2) {
+  return unique(value1).sort().join(',') == unique(value2).sort().join(',');
+}
+
+module.exports = {
+  unique: unique,
+  same: same
+};