redux-devtools/packages/redux-devtools-trace-monitor/.babelrc

{
  "presets": ["@babel/preset-env", "@babel/preset-react", "@babel/preset-flow"],
  "plugins": [
    [
      "@babel/plugin-transform-runtime",
      {
        "regenerator": true
      }
    ],
    ["@babel/plugin-proposal-decorators", { "legacy": true }],
    "@babel/plugin-proposal-class-properties"
  ]
}