Disabling Containers from about:addons wrongly removes the add-on

[SoftVision-CiprianMuresan]

[Affected versions]:

• Firefox 54.0.1 and up
• Containers 2.3.0

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]:

• Latest Containers add-on was previously installed on a clean profile.

[Steps to reproduce]:

1. Go to about:addons->Extensions tab.
2. Click the Disable button for the Containers add-on.
3. Observe the behavior.

[Expected result]:

• The add-on is disabled.

[Actual result]:

• The add-on is removed.

[Notes]:

• Attached a screen recording of the issue:
  

[kjozwiak]

This is happening on both @testpilot-containers and @shield-study-containers using 13cd601:

kjozwiak:testpilot-containers kjozwiak$ git log -1
commit 13cd601212dfa76c957a9f2c3cea91799e4ce644 (HEAD -> master, origin/master, origin/HEAD)
Merge: 6533c74 bc847b5
Author: luke crouch <luke.crouch@gmail.com>
Date:   Tue Jun 20 10:18:46 2017 -0500

    Merge pull request #602 from jonathanKingston/edit-restyle
    
    Edit restyle

Currently not reproducible using containers_experiment-2.3.0-fx.xpi which was retrieved from the test pilot page so this is definitely a regression that was introduced this version.

I'm not sure how this issue might affect the removal of the shield study once it's complete.

[groovecoder]

Pretty sure this is caused by the shield study library code. I'll dig into it.

[groovecoder]

Okay, we can fix this for the @testpilot-containers version, but the shield library is hard-coded to un-install the add-on completely when the user disables it.

[SoftVision-CiprianMuresan]

The issue is no longer reproducible on the Test Pilot version of containers.
I've also verified that disabling still removes the add-on on the Shield version of containers.
Marking as verified.