Android上canvas滑动到控件外，touchend不触发
Android上canvas滑动到控件外，touchend不触发，iPhone上没有问题。
极容易复现
（xml代码）
<view class="container">
<canvas canvas-id="canvasId1" style="width:200prx;height:200prx;background:#222;" bindtouchstart='touch1' bindtouchmove='touch1'bindtouchend='touch1' bindtouchcancel='touch1'></canvas>
<canvas canvas-id="canvasId2" style="width:200prx;height:200prx;background:#f42;margin-top:30rpx" bindtouchstart='touch2'bindtouchmove='touch2' bindtouchend='touch2' bindtouchcancel='touch2'></canvas>
<view>{{msg}}</view>
</view>
（js代码）
Page({
data: {
msg:""
},
//事件处理函数
touch1: function(e) {
let msg = "canvas1:"+ e.type + " x:"+ parseInt(e.changedTouches[0].x) + " y:" +parseInt(e.changedTouches[0].y)
console.log(msg)
this.showMsg(msg)
},
touch2: function (e) {
let msg = "canvas2:" + e.type + " x:" + parseInt(e.changedTouches[0].x)+ " y:" + parseInt(e.changedTouches[0].y)
console.log(msg)
this.showMsg(msg)
},
showMsg:function(msg){
this.setData({
msg:msg
})
}
})
