Steps to reproduce and a minimal demo of the problem

http://plnkr.co/edit/QcbOZCLEMxDqB9Hal0ef?p=preview

Current behavior

Just press a in the search field to get a list of options and then press down key. The selected result is constantly reset. Selecting one will keep the single result open.

Expected/desired behavior

Here's a version of the plunkr without angular2-polyfills.js to show the difference.

http://plnkr.co/edit/FIygVljA8bIWaoAFehDr?p=preview

Any insights in why just including angular2-polyfills.js causes this inwanted change would be great. At first I thought it was an issue which could be solved by ngZone.runOutsideAngular but that was before I narrowed it down to simply including angular2-polyfills.js