Gets the local CSS Y position for the element

@return {Number}
function() {
            var me = this,
                offsetParent = me.dom.offsetParent,
                y = me.getStyle('top');

            if (!y || y === 'auto') {
                y = 0;
            } else if (me.pxRe.test(y)) {
                y = parseFloat(y);
            } else {
                y = me.getY();
                if (offsetParent) {
                    y -= Element.getY(offsetParent);
                }
            }

            return y;
        }