Screen reader doesn't voice value in mat-select when changed with arrow keys

[calebegg]

When you change the selection in a mat-select using the arrow keys (without opening the actual listbox), the value of the selection changes but is not announced to a screen reader user

Demoable on https://material.angular.io/components/select/overview with Chromevox or JAWS

Specifically:

1. Tab onto a mat-select
2. Press the down arrow

The selection shown changes, change events fire, but nothing is read aloud by the screen reader.

[jelbourn]

This is part of #11083

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}