message: Add isDone() method to blockers
diff: @@ -9,6 +9,7 @@ import RSVP from 'rsvp';
  export interface Blocker {
  done: () => void;
  errored: (e: any) => void;
  + isDone: () => boolean;
  }
  export enum Events {
  @@ -39,6 +40,7 @@ export default class Ready extends Service.extend(Evented) {
  return {
  done: () => null,
  errored: () => null,
  + isDone: () => true,
  };
  }
  const id = this.incrementProperty('lastId');
  @@ -46,6 +48,7 @@ export default class Ready extends Service.extend(Evented) {
  return {
  done: this.doneCallback(id),
  errored: this.errorCallback(),
  + isDone: () => !this.blockers.includes(id),
  };
  }
  