The links and buttons from the door hanger display double focuses

[SoftVision-CarmenFat]

[Affected versions]:

• Firefox Release v63.0 and up

[Affected Platforms]:

• All Windows
• All Linux
• All Mac

[Prerequisites]:

• Have a Firefox profile with the latest version of the "Price Wise" add-on (9.0.0) downloaded from (download link).

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites.
2. Click the Price Wise toolbar button.
3. Press the "Tab" key and observe the way the "Feedback" button is focused.

[Expected result]:

• The button is surrounded only by blue borders.

[Actual result]:

• The button is surrounded by blue borders and also by dotted lines.

[Notes]:

• This issue is reproducible with all the buttons and links from the door hanger;
• Here is a screen recording of the issue: