The confirmation bar wrongly remains displayed when removing the experiment

[SoftVision-CarmenFat]

[Affected versions]:

• Firefox 58.0.2 and above
• Snooze Tabs 1.1.0

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]:

• Have a Firefox profile with the latest Snooze Tabs add-on version (https://github.com/bwinton/SnoozeTabs/releases/tag/1.1.0) loaded as a temporary add-on.
• "Ask for confirmation when snoozing tabs" checkbox is checked.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites and navigate to a website (e.g. "www.wikipedia.org").
2. Click on the "Snooze tabs" toolbar button.
3. Click on one of the snooze options (except "Pick a Date/Time").
4. Go to "about:addons" page and click the "Extensions" option.
5. Click the "Remove" button specific to Snooze Tabs experiment.
6. Go back to the website from step 1 and observe the content page.

[Expected result]:

• The confirmation bar is no longer displayed.

[Actual results]:

• The confirmation bar is displayed and none of its buttons is functional.

[Notes]:

• This is also reproducible with the Test Pilot version of Snooze Tabs.
• Attached a screencast of the issue: