code: function makeRootPlugin(ModulesInRootPlugin, name, root) {
    if(typeof root === "string")
      return new ModulesInRootPlugin(name, root);
    else if(Array.isArray(root)) {
      return function() {
        root.forEach(function(root) {
          this.apply(new ModulesInRootPlugin(name, root));
        }, this);
      };
    }
    return function() {};
  }
docs: /* eslint-disable from https://github.com/webpack/webpack/blob/v1.13.0/lib/WebpackOptionsApply.js#L365