echars 饼图有条裂缝？

option = {
legend: {
y : 'bottom',
data:['直接访问','邮件营销']
},
calculable : false,
series : [
{
name:'访问来源',
type:'pie',
radius : ['0','55%'],
data:[
{value:335, name:'直接访问'},
{value:310, name:'邮件营销'}
]
}
]
};

http://q.cnblogs.com/q/68074/