Add filter-replace

Author: addyosmani

filter-replace.js

@@ -0,0 +1,18 @@
+PolymerExpressions.prototype.replace = function (str, old, new_, maxCount) {
+    var res = str;
+    var last = res;
+    var count = 1;
+    res = res.replace(old, new_);
+
+    while (last != res) {
+        if (count >= maxCount) {
+            break;
+        }
+
+        last = res;
+        res = res.replace(old, new_);
+        count++;
+    }
+
+    return res;
+}