Description of problem:
When captive portal is detected, there is displayed login window, but without content. Looking at the list of processes, I see two processes hanging around, loading my system:

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                                                                                                                                        
17832 gdm       20   0 2281580  73876  56952 S  77,6  0,6  10:11.41 WebKitWebProces                                                                                                                                
 8642 gdm       20   0 2769492  81068  65344 S  42,4  0,7   5:49.88 gnome-shell-por      

They seems to be stuck.


Version-Release number of selected component (if applicable):
$ rpm -qf /usr/libexec/gnome-shell-portal-helper
gnome-shell-3.21.4-1.fc25.x86_64

$ rpm -qf /usr/libexec/webkit2gtk-4.0/WebKitWebProcess
webkitgtk4-2.13.4-1.fc26.x86_64


How reproducible:
Always


Steps to Reproduce:
1. Connect to WiFi with captive portal.
2. The login dialog is displayed without content => no way how to log in.
3. The processes mentioned above are still hanging around

Actual results:
The login dialog does not work and some processes are left around.


Expected results:
The login dialog works just fine.


Additional info: