I don't know if Iron is on the list of supported browsers, unfortunately there is no where that I'm aware of that you can check what is approved.
However you could opt-in Iron to use the web shield.
You need to edit the avast4.ini file [WebScanner] section and ad the executable file name for Iron.
[WebScanner]
OptinProcess=executableFileName.exe
Or you could set its proxy settings (in connections, don't use Iron so don't know the exact location) to use the web shield.