An infinite spinner is displayed when opening a non-owner shot taken from the latest Nightly Try build if uBlock Origin is installed

[SoftVision-CiprianMuresan]

[Notes]:

• The issue is not reproducible if the first ever shot is shared (Browser Console errors). However it it reproducible with all subsequent shots.
• The issue is also reproducible on Chrome with uBlock Origin installed.
• If I disable uBlock Origin and refresh the page, the image is loaded correctly.
• The issue is not reproducible if the page is shared from a custom build using the Page Shot dev server.
• The issue is not reproducible on Chrome or Firefox with AdBlock Plus installed.

[Affected versions]:

• Firefox 52 and up.

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]:

• Have uBlock Origin installed on a clean profile.

[Steps to reproduce]:

1. Open the browser and profile from prerequisites.
2. Open a non-owner shot taken with the Nightly try build. (eg. https://screenshots.firefox.com/8JSV1y1KERYowIT3/www.imdb.com)
3. Observe the browser behavior.

[Expected result]:

• The page is loaded and the image is displayed.

[Actual result]:

• The page is loaded, but the spinner loops infinitely and the image is not displayed.

[Additional notes]:

• Here is a screen shot of the issue:
  
• Here are the errors shown in the browser console:
  

[ianb]

This was probably fixed in #2798, but #2792 double-fixes it – the first makes it so uBlock doesn't keep JavaScript from loading, and the second makes it so if the JavaScript bundle fails the image will still be displayed.

[SoftVision-CiprianMuresan]

The issue is no longer reproducible with shots taken with Screenshots from the latest Nightly build.