registerUrl(name, input) {
    var url = new utils_url["a" /* default */](input);
    this._themes[name] = {
      "url": url.toString()
    };

    if (this._injected[name] || name == 'default') {
      this.update(name);
    }
  }
Register a url
@param {string} name
@param {string} input