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.
I think there is always one of those buttons that will be activated. So instead of binding this, what about binding the button that is displayed ?

So something like:
var button = this.menuButton || this.bookmarkButton;

And uses button directly ?