Add reverse filter.

Author: addyosmani

filter-reverse.js

@@ -0,0 +1,13 @@
+/**
+ * Reverse a supplied value
+ * @param  {string} input
+ * @return {string} reversed string
+ */
+PolymerExpressions.prototype.reverse = function (input) {
+    input = input || '';
+    var out = "";
+    for (var i = 0; i < input.length; i++) {
+        out = input.charAt(i) + out;
+    }
+    return out;
+};