dispatchEvent returns boolean (#5117)

Author: aomarks

lib/utils/templatize.html

@@ -246,8 +246,10 @@
        * dispatch events safely no-op.
        *
        * @param {Event} event Event to dispatch
+       * @return {boolean} Always true.
        */
        dispatchEvent(event) { // eslint-disable-line no-unused-vars
+         return true;
       }
     }
 

types/lib/utils/templatize.d.ts

@@ -71,8 +71,9 @@ declare class TemplateInstanceBase extends
    * dispatch events safely no-op.
    *
    * @param event Event to dispatch
+   * @returns Always true.
    */
-  dispatchEvent(event: Event|null): any;
+  dispatchEvent(event: Event|null): boolean;
 }
 
 declare namespace templateInfo {