Link-based popup blocking stopped working in Firefox 79

Background

Starting with Firefox 79, <a target="_blank"> links imply rel="noopener", and documents created with the noopener flag aren't reported through webNavigation.onCreatedNavigationTarget on Firefox, hence are ignored by Adblock Plus' popup blocking logic.

Steps to reproduce

1. Open https://testpages.adblockplus.org/en/filters/popup on Firefox 79 or higher.
2. Add filter ||testpages.adblockplus.org/testfiles/popup/link.html^$popup to the extension.
3. Refresh the test page and click Trigger link based popup

Observed behavior

The popup is not blocked.

Expected behavior

The popup should be blocked.