Add support for Webpack's BannerPlugin

[guilhermesimoes]

Adding the following BannerPlugin to a build:

new BannerPlugin({
  banner: 'console.log("hello world");',
  raw: true,
}),

causes webpack-bundle-analyzer not to return an accurate size. This is because when webpack-bundle-analyzer parses a bundle it requires the first thing in the bundle to be the start of a webpack module. It would be great if the parsing logic could be changed to take this plugin into account.

[jameshoward]

We are having a similar issue when using the Sentry Webpack plugin, which injects a script to the top of the bundle using BannerPlugin. This seems to break the parseBundle function in parseUtils.js because, after minification, the bundle ends up starting like this:

!function(){ /* Sentry code here */ }(),(()=>{ /* webpack module here */})();

When walking the AST in parseBundle, this is matched as a single ExpressionStatement but it doesn't match any of the conditions for finding the Webpack module.

This in turn means that node_modules are not correctly split out from the src/ in our project when using this plugin.

There's an example at https://github.com/jameshoward/webpack-sentry-demo but an even simpler reproduction is to inject code with a BannerPlugin, provided that code won't be overly-stripped-out by Terser:

// webpack.config.js
  …
  plugins: [
    new webpack.BannerPlugin({
      banner: '(function() { console.log(window); })();',
      raw: true
    })
  ]