message: fix(devtools): dont leak flat and indexed nodes
diff: @@ -41,7 +41,7 @@ export class ComponentDataSource extends DataSource<FlatNode> {
  private _differ = new DefaultIterableDiffer(trackBy);
  private _expandedData = new BehaviorSubject<FlatNode[]>([]);
  private _flattenedData = new BehaviorSubject<FlatNode[]>([]);
  - private _nodeToFlat = new Map<IndexedNode, FlatNode>();
  + private _nodeToFlat = new WeakMap<IndexedNode, FlatNode>();
  private _treeFlattener = new MatTreeFlattener(
  (node: IndexedNode, level: number) => {
  @@ -99,7 +99,6 @@ export class ComponentDataSource extends DataSource<FlatNode> {
  this._flattenedData.next(this.data);
  movedItems.forEach(i => this._nodeToFlat.set(i.original, i));
  - removedItems.forEach(item => this._nodeToFlat.delete(item.original));
  newItems.forEach(i => (i.newItem = true));
  return newItems;
  