Reproduction

Here's a repro on stackblitz: https://stackblitz.com/edit/angular-i6q9p5

Steps to reproduce:

1. Press on the select
2. Change selection using keyboard down arrow
3. My code adds 10 new items each 5 seconds so you should be able to reproduce my issue
4. The view remove the selected active item and if you press down again when new items are there, the active item will start back from top

Expected Behavior

When adding new items, the panel should preserve the current active item and scroll (unless current item is not there anymore).

Actual Behavior

The view remove the selected active item and if you press down again when new items are there, the active item will start back from top

Environment

Angular CLI: 8.1.1
Node: 12.6.0
OS: win32 x64
Angular: 8.1.1
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router, service-worker

Package Version

@angular-devkit/architect 0.800.6
@angular-devkit/build-angular 0.801.1
@angular-devkit/build-optimizer 0.801.1
@angular-devkit/build-webpack 0.801.1
@angular-devkit/core 8.1.1
@angular-devkit/schematics 8.1.1
@angular/cdk 8.0.0
@angular/flex-layout 7.0.0-beta.23
@angular/material 8.0.2
@angular/material-moment-adapter 8.0.2
@ngtools/webpack 8.1.1
@schematics/angular 8.0.0
@schematics/update 0.801.1
rxjs 6.5.2
typescript 3.4.5
webpack 4.35.2