[Enhancement] The Firefox icon should have a larger size in the system notification messages displayed on Windows 10

[Softvision-RemusDranca]

[Affected versions]:

• Firefox Nightly 65.0a1 (Build ID 20181125220116)

[Affected Platforms]:

• Windows 10

[Prerequisites]:

• Have a new Firefox profile with the latest version of the "Email Tabs" add-on (0.1.7808) custom build.
• You are not logged in in any email provider.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites and navigate to "https://www.wikipedia.org/".
2. Click the "Email Tabs" toolbar button and select an email provider.
3. Click the "Email Tabs" button and observe the and system notification message.

[Expected result]:

• The Firefox icon is displayed and it has a proportional size .

[Actual result]:

• The Firefox icon is displayed, but in an considerably small size.

[Notes]:

• The Firefox icon has a small size on all "Email Tabs" system notifications.
• Attached is a screen recording of the issue: