Typing in Autosize textarea on Firefox mobile causes unexpected characters to appear

Reproduction

Steps to reproduce:

1. Install Firefox mobile (https://play.google.com/store/apps/details?id=org.mozilla.firefox, versionName=68.4.2, versionCode=2015676155)
2. Navigate to https://material.angular.io/components/input/examples (currently version 8.2.3)
3. Scroll down to the the 'Auto-resizing textarea' section
4. Tap in the 'Autosize textarea' box
5. Type a few characters

Expected Behavior

Characters appear exactly as typed

Actual Behavior

• Extraneous characters appear.
• Looks like the Firefox mobile browser and Angular Material are fighting each other, causing extra characters to appear

Environment

• Angular: (whatever https://material.angular.io/components/input/examples is using)
• CDK/Material: 8.2.3
• Browser(s):
• Operating System (e.g. Windows, macOS, Ubuntu):