Bug 1048927 - Enable 'add to home' for all web content. r=vingtetun

This enables the 'add to home' option for all web content and not just
e.me results.
Do you mean useCombinedChrome? It's not exactly the same, so I can't really reuse it. I needed to catch the situation that there's a visible bookmark option and this combination of flags seemed to be what I wanted... Maybe I can play around a bit more to find a better way though.