Fx.Scroll toElementEdge doesn't account current scroll

[megawac]

The Fx.Scroll toElementEdge doesnt consider the parent elements scroll position when determining if scrolling is necessary. This causes the effect not to run when it should be valid.

I updated the function in my project with the following quick fix which seems to do the trick:

toElementEdge: function(el, axes, offset){
        axes = axes ? Array.from(axes) : ['x', 'y'];
        el = document.id(el);
        var to = {},
            coords = el.getCoordinates(this.element),
            scroll = this.element.getScroll(),
            containerSize = this.element.getSize(),
            edge = {
                x: coords.right + scroll.x,
                y: coords.bottom + scroll.y
            };

        ['x', 'y'].each(function(axis){
            if (axes.contains(axis)){
                if (edge[axis] > scroll[axis] + containerSize[axis])
                    to[axis] = edge[axis] - containerSize[axis];
                // if (edge[axis] < scroll[axis])
                //  to[axis] = edge[axis];
            }
            if (to[axis] == null) to[axis] = scroll[axis];
            if (offset && offset[axis]) to[axis] = to[axis] + offset[axis];
        }, this);

        if (to.x != scroll.x || to.y != scroll.y)
            this.start(to.x, to.y);
        return this;
    }

[megawac]

Cross posting from #239