Search for a parent scope to eval within

I wanted to have content within functions be evaluated if possible too.
This is mostly a start, and it could be taken further.

With this code, the following will work:

	var a = function(){
		var f = 'what';		// undefined
		f + 'who';			// "whatwho"
	}

Function params throw a wrench, because the variables are never "reset".
For example:

	var a = function(f){
		f += 'what';		// "whatwhatwhatwhat"
		f + 'who';			// "whatwhatwhatwhatwho"
	}

The repeat happens every time the area is reevaluated. I thought about
scanning for args in the function, and then prepending 'f="default"' to
the eval'ed string. But it's impossible to know what to initialize them
with.