message: Move new-item tracking to IndexedDB
diff: import angular from 'angular';
  import _ from 'underscore';
  import { sum, count } from '../util';
  +import idbKeyval from 'idb-keyval';
  angular.module('dimApp')
  .factory('dimStoreService', StoreService);
  @@ -1435,15 +1436,16 @@ function StoreService(
  function loadNewItems(activePlatform) {
  if (activePlatform) {
  - return SyncService.get().then(function processCachedNewItems(data) {
  - return new Set(data[newItemsKey()]);
  - });
  + const key = newItemsKey();
  + // Clean out old new-items from the Sync Service, we store in IndexedDB now.
  + SyncService.remove(key);
  + return idbKeyval.get(key).then((v) => v || new Set());
  }
  return $q.resolve(new Set());
  }
  function saveNewItems(newItems) {
  - SyncService.set({ [newItemsKey()]: [...newItems] });
  + return idbKeyval.set(newItemsKey(), newItems);
  }
  function newItemsKey() {
  