message: fix(fromEvent): Defines toString to fix Closure compilations
diff: @@ -2,6 +2,8 @@ import { Observable } from '../Observable';
  import { isFunction } from '../util/isFunction';
  import { Subscriber } from '../Subscriber';
  +const toString: Function = Object.prototype.toString;
  +
  export type NodeStyleEventEmitter = {
  addListener: (eventName: string, handler: Function) => void;
  removeListener: (eventName: string, handler: Function) => void;
  