The "#" promo from the header of the Screenshots pages is not displayed if you have an adblocker installed

[SoftVision-CosminMuntean]

[Affected versions]:

• Nightly 64.0a1
• Screenshots 34.0.0 dev

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]:

• The "xpinstall.signatures.required" boolean pref is set to "false".
• The "extensions.legacy.enabled" boolean pref is set to "true".
• Have the Screenshots 34.0.0 dev version installed from here, on a new clean profile.
• Have the uBlock Origin or Adblock Plus installed on the created profile.
• You are not logged in into FxA.

[Steps to reproduce]:

1. Open the Firefox browser with the new profile from prerequisites and navigate to any website.
2. Save a selection on the page.
3. Observe the header of the page.

[Expected result]:

• The "#" promo is displayed.

[Actual results]:

• The "#" promo is not displayed.

[Notes]:

• I have managed to reproduce this issue with uBlock Origin, Adblock Plus, AdBlocker Ultimate.
• Here is a screen recording of the issue:
  

[SoftVision-CosminMuntean]

It seems that the issue is also reproducible for the Firefox promo bar displayed in the non-Firefox browser at the header of the page.
For example, if you have an adblocker on chrome and you open a shot the Firefox promo bar is not displayed,
Here is a screenshot on Chrome with uBlock installed:

Here is a screenshot on Chrome without any adblocker installed:

[johngruen]

Let's change the class name?

[SoftVision-CosminMuntean]

I have verified this issue using the latest Screenshots (34.0.0) dev version and is no longer reproducible. Tested on Windows 7 x64, Mac 10.13 and Arch Linux. 4.12.