Webpack const is not converted to var

I've this webpack configuration for js rules:

test: /\.js$/,
  exclude: [/node_modules/],
  loader: 'babel-loader',
  options: {
    presets: [['es2015', { modules: false }]],
    plugins: ["transform-vue-jsx","transform-runtime"],
}

When i compile with webpack 3.5 this line is created:

/* WEBPACK VAR INJECTION */(function(process) {const isWin = process.platform === 'win32';

That const is the only inside the bundles and makes IE10 trigger a syntax error. This didn't happen with webpack 2. Do you know why this is happening ? I'm on windows 10, may it be the cause ?