        }
        this.fire('iron-form-invalid');
        return;
      }

      var json = this.serialize();

      // Native forms can also index elements magically by their name (can't make
      // this up if I tried) so we need to get the correct attributes, not the
      // elements with those names.
      this.request.url = this.getAttribute('action');
      this.request.method = this.getAttribute('method');
      this.request.contentType = this.contentType;
      this.request.withCredentials = this.