Broken screenshot preview image

[DPX-designer]

Having tried on multiple websites I receive the same results:

1. Select "Take a screenshot" from the address bar menu
2. Click Save Visible
3. The modal appears presenting a broken preview image
4. I am still able to download the captured image however

Tested on Firefox Nightly 82.0a1

The bug is not present in Firefox 78.0.2 or Firefox 80.0.1

[sfoster]

Thanks for spotting this. I can reproduce in Nightly.

[sfoster]

mozregression points at https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=fe1f580e78c1f07163d3e129a10fb8e8ff9c5f9f&tochange=626c0384ddb82f690f173af5730a5e07b0d28f53 and Bug 1658878 - Isolate BlobURLs per agent-cluster specifically, which sounds entirely plausible.