https://polymer-library.polymer-project.org/3.0/docs/devguide/events#custom-events after this change, we should be able to remove FireBehavior Change-Id: Iad2fc847eb8855d4fd4349bcc9aa74c8ac2d8236
https://polymer-library.polymer-project.org/3.0/docs/devguide/events#custom-events after this change, we should be able to remove FireBehavior Change-Id: Iad2fc847eb8855d4fd4349bcc9aa74c8ac2d8236