Gets the local CSS X position for the element

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

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

            return x;
        }