Revert "webpack: apply ExtractTextPlugin to vendor.css"

This reverts commit 7c9edb35d0.

src/FilterLists.Web/webpack.config.js

@@ -58,7 +58,6 @@ module.exports = (env) => {
                             comments: false
                         }
                     }),
-                    new ExtractTextPlugin("vendor.css"),
                     new ExtractTextPlugin("site.css")
                 ])
         }