 Polymer data-binding features as well as
       * declarative event listeners.  Event listeners and inline computing
       * functions in the template will be called on the host of the template.
       *
       * The constructor returned takes a single argument dictionary of initial
       * property values to propagate into template bindings.  Additionally
       * host properties can be forwarded in, and instance properties can be
       * notified out by providing optional callbacks in the `options` di