[Affected versions]: Nightly 66.0a1 [Affected platforms]: Platforms: Windows 17 x 64, Mac OS X 10.14 and Ubuntu 16.04 x64. [Steps to reproduce]: 1. Open Delivery Console: https://delivery-console.stage.mozaws.net/ 2. Add a new heartbeat recipe, fill all the fields correctly set Post Answer URL and LEARN MORE URL. 3. Open FF having the pre-requisites set and open the browser console. 4. Click on learn more link or interact with the hearbeat. 5. Close browser (and console) and reopen them. [Expected result]: Post Answer URL and Learn More URL should redirect you to the links set in "Post Answer URL" and "Learn More URL" fields. [Actual result]: Post Answer URL and Learn More URL aren't working.

I forgot to mention an important note that the issue only happens when "about:plugins" or "about:support" links are set in Post Answer URL and Learn More URL fields.