The Pinterest login panel is displayed several times even after previously submitting the valid credentials

[SoftVision-CarmenFat]

[Affected versions]:

• Firefox Nightly 68.0a1 (2019-04-22)

[Affected Platforms]:

• All Windows
• All Linux
• All Mac

[Prerequisites]:

• The "xpinstall.signatures.required" boolean pref is set with the "false" value.
• Have the “facebook_container-2.0.0” add-on installed.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites.
2. Navigate to https://www.pinterest.com website.
3. Click the Facebook Container badge.
4. Click inside the blue pop-up.
5. Enter your valid credentials and press the "Log in" button.
6. Observe the behavior.

[Expected result]:
Step 6 - You are logged into your Pinterest account.

[Actual result]:
Step 6 - The Pinterest login panel is displayed again.

[Notes]:

• By clicking again the Facebook Container badge will open another login panel in a new window, which automatically closes after ~3 seconds, and the previous login page refreshes.
• You are logged in to your Pinterest account only after the 4th try.
• Please see the attached screen recording with the issue:

[maxxcrawford]

See #283 – Duplicate issue. The automatic page refresh solves this.