test '0' and ''echarts 折线配置项内容和展示

                      var option = {
                    xAxis: {
                        data: ['a', 'b', 'c', 'd', 'e']
                    },
                    yAxis: {
                    },
                    series: [{
                        type: 'line',
                        data: ['0', '0', '0', '', '']
                    }]
                };