Focus monitor malfunction on IOS

[kirill-chirkov-at-clouty]

Reproduction

Steps to reproduce:

1. Open https://material.angular.io/cdk/a11y/overview with IOS device
2. Click on any button inside focus monitor demonstration
3. See that touch event is not visually happening

Expected Behavior

Touch origin is expected to be set on button

Environment

• Angular: 8+
• CDK/Material: 8.1.3
• Browser(s): Safari
• Operating System (e.g. Windows, macOS, Ubuntu): IOS 12.4

[jelbourn]

Possibly related to #15517