Quickly clicking volume UI element results in Fullscreen transition

[fcolley]

Have you read the FAQ and checked for duplicate open issues?
Yes

What version of Shaka Player are you using?
Build: Shaka v2.5.3-master-38-gfd326951 (uncompiled)

Can you reproduce the issue with our latest release version?
Yes

Can you reproduce the issue with the latest code from master?
Yes

Are you using the demo app or your own custom app?
Shaka Player Demo

What browser and OS are you using?

What did you do?
Environment: Linux, Mac, Win10, etc
Build: Shaka v2.5.4-master-7-g7c271bab (uncompiled)

Steps:

1. Navigate to: https://nightly-dot-shaka-player-demo.appspot.com
2. Launch video asset and click the volume icon to mute the audio
3. Double click the volume icon to switch back and forth quickly

Actual Result:
The screen toggles into Fullscreen mode

Expected:
If you click on the volume UI element quickly it's not expected that you would go into Fullscreen mode