scripts/build/bundler.js/getBabelConfig
function getBabelConfig(bundle) {
  const config = {
    babelrc: false,
    plugins: bundle.babelPlugins || [],
    compact: bundle.type === "plugin" ? false : "auto",
  };
  if (bundle.type === "core") {
    config.plugins.push(
      require.resolve("./babel-plugins/transform-custom-require")
    );
  }
  const targets = { node: "10" };
  if (bundle.target === "universal") {
    targets.browsers = [
      ">0.5%",
      "not ie 11",
      "not safari 5.1",
      "not op_mini all",
    ];
  }
  config.presets = [
    [
      require.resolve("@babel/preset-env"),
      {
        targets,
        exclude: ["transform-async-to-generator"],
        modules: false,
      },
    ],
  ];
  config.plugins.push([
    require.resolve("@babel/plugin-proposal-object-rest-spread"),
    { loose: true, useBuiltIns: true },
  ]);
  return config;
}