For users who remove the searchbar/box and just use the "omnibar"
approach to searching it makes little sense for oneLiner to add
a search button to the toolbar.
* Declares search as a var inside the function, rather than use a let
statement, so that it can be modified inside an if statement
* If statement detects whether searchbar is enabled and only
generates button, etc if it is.
This may well be Linux/Fedora specific, but using oneLiner meant
that the appmenu button (the thing you get if you don't show the
menu bar) always displayed inbetween the urlbar and the tabs. And
to me that just looked stupid. So this forces it to the far left.
No idea what happens on other platforms with these changes.