tabBar的borderStyle设置成black后，开发工具模拟器tabbar会多一条白条，只在开发工具能够复现，而是是有底部安全区域的机型上，真机正常。

复现代码：

 "tabBar": {
    "color": "#161823",
    "selectedColor": "#FE2C55",
    "borderStyle": "black", // 写个"borderStyle": "black"就能复现
    "list": [{
        "pagePath": "pages/index/index",
        "text": "主页",
        "iconPath": "./assets/house.png",
        "selectedIconPath": "./assets/house-selected.png"
      },
      {
        "pagePath": "pages/category/category",
        "text": "分类",
        "iconPath": "./assets/module.png",
        "selectedIconPath": "./assets/module-selected.png"
      },
      {
        "pagePath": "pages/order-list/order-list",
        "text": "订单",
        "iconPath": "./assets/doc.png",
        "selectedIconPath": "./assets/doc-selected.png"
      },
      {
        "pagePath": "pages/custom-login/custom-login",
        "text": "我的",
        "iconPath": "./assets/user.png",
        "selectedIconPath": "./assets/user-selected.png"
      }
    ]
  }