UserAgent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:54.0) Gecko/20100101 Firefox/54.0

Steps to reproduce the problem:
1. Set default system browser different than Chrome
2. Create a desktop application of the website (Settings - More tools - Add to desktop)
3. Start the application and open a link that is supposed to open a new browser window (outside of application)

What is the expected behavior?
The link should be opened in the default system browser

What went wrong?
The link is opened in chrome

Did this work before? N/A 

Chrome version: 59.0.3071.115 (Official Build) (64-bit)  Channel: stable
OS Version: fedora 26
Flash Version: Shockwave Flash 26.0 r0