Fix #1983 : Object properties can be mangle now.
Fix #1983 : Object properties can be mangle now.

Use the following config:

```js
{
  plugins: [
    new webpack.optimize.UglifyJsPlugin({
        mangle: {
          props: {
            regex: /_$/
          },
        },
      }),
  ]
}
```
mishk0/webpack,webpack/webpack,jescalan/webpack,sdawson/webpack,webpack/webpack,pugnascotia/webpack,NekR/webpack,ts-webpack/webpack,pugnascotia/webpack,ts-webpack/webpack,cesarandreu/webpack,NekR/webpack,halfzebra/webpack,EliteScientist/webpack,EliteScientist/webpack,nkzawa/webpack,ts-webpack/webpack,rlugojr/webpack,g0ddish/webpack,ianwcarlson/webpack,sdawson/webpack,rlugojr/webpack,SimenB/webpack,pugnascotia/webpack,jescalan/webpack,webpack/webpack,halfzebra/webpack,halfzebra/webpack,cesarandreu/webpack,SimenB/webpack,cesarandreu/webpack,ianwcarlson/webpack,jamestautges/webpack,jamestautges/webpack,mishk0/webpack,nkzawa/webpack,rlugojr/webpack,SimenB/webpack,nkzawa/webpack,jescalan/webpack,webpack/webpack,SimenB/webpack,g0ddish/webpack,ts-webpack/webpack,g0ddish/webpack