Login Button popup blocked on Windows for allowed sites

[hillbrad]

• Facebook Container Version: 2.0.3
• Operating System + Version: Windows (all)
• Firefox Version: 70.0
• Other installed Add-ons + Version + Enabled/Disabled-Status: None

Actual behavior

On sites where the user has explicitly added a site to the allowed sites in Facebook Container, a substantial delay is introduced when clicking on the Facebook Login button, which causes the popup blocker to trigger.

Expected behavior

Popups behave normally (opening with user gesture) on allowed sites.

Steps to reproduce

1. Go to Pinterest.com with Facebook Container disabled
2. Click "Continue with Facebook"
3. Popup opens
4. Enable Facebook Container
5. Click Facebook Container menu and allow Pinterest.com
6. Close popup and reload Pinterest.com
7. Click "Continue with Facebook"
8. Observe delay and "Firefox prevented this site from opening a popup window."

Notes

The popup opens originally at step 5, but return visits all have the blocker triggered by the large async delay introduced which is presumably causing the user gesture flag to be lost.

[hillbrad]

This behavior is not observed on OS X.

[maxxcrawford]

Is this still reproducible on the latest version of the add-on (2.1.1) and Firefox (77.0.1)?