解决：Flutter canvaskit Failed to d

flutter web 工程第一次运行时会下载 web sdk, canvaskit,
但是在国内常常卡在Downloading canvaskit就下载失败了

解决办法：使用国内的镜像
export FLUTTER_STORAGE_BASE_URL=https://storage.flutter-io.cn
再次运行时如果出现了
Flutter assets will be downloaded from https://storage.flutter-io.cn. Make sure you trust this source!那基本就成功了，没有就重启下电脑
详细设置:flutter mac 三分钟 环境搭建